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The Bermuda islands:a contribution to th

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THE

BERMUDA ISLANDS:

A CONTRIBUTION TO THE PHYSICAL HISTORY AND ZOOLOGY OF THE

SOMERS ARCHIPELAGO.

WITH AN EXAMINATION OF THE STRUCTURE OF CORAL REEFS.

RESEARCHES UNDERTAKEN UNDER THE AUSPICES OF THE ACADEMY OF NATUBAL SCIENCES OF PHILADELPHIA.

BY

ANGELO HEILPRIN, F.c.s.a.,F.a.GEOGR. SOC.,

Curator-in-Charge of, and Professor of Invertebrate Paleontology at, the Academy of Natural Sciences of Philadelphia; Professor of Geology at the Wagner Free Institute of Science; Member of the American Philosophical Society, ete.

WITH ADDITIONS BY

Prof. J. Puayrarr McMurricn, Mr. H. A. Pirspry, Dr. GEorGE Marx, Dr. P. R. UBLER, and Mr. C. H. Botimay.

PHILADELPHIA: PUBLISHED BY THE AUTHOR. ACADEMY OF NaTURAL SCIENCES.

1889. ©

CopyRIGHT, 1889, By A. HEiLprin.

PREEA OF RINDER & KELLY, Printers and Publishers, Vhilad'u

Tue observations recorded in the following pages are the outcome of a vacation-journey undertaken in the summer of 1888 in company with a class of students from the Academy of Natural Sciences of Philadelphia. My main object in visit- ing the islands was to satisfy my mind on certain points con- nected with the structure and physiognomy of coral reefs, to the study of which the Bermudas offer special advantages. I contemplated but little work in zoology, and that which was accomplished may be considered supplemental to the plan of work originally laid out. It was not until my return to Phil- adelphia that I was made aware of the extent of the zoological material collected by us, and how little systematic study of the fauna of the region had been made prior to our visit. Some of our material still awaits examination; for the elaboration of that portion which is delineated in the present volume I am largely indebted to the labors of a number of specialists who have kindly volunteered theirassistance. In thisconnection I desire to acknowledge my indebtedness to Prof. J. Playfair

MeMurrich, formerly of Haverford College; to Mr. H. A. Pilsbry, of the Academy of Natural Sciences; to Dr. George Marx, of Washington; to Dr. P. R. Uhler, of Baltimore ; to the late Mr. C. H. Bollman, of Bloomington, Ind.; and to two of my immediate assistants, Messrs. J. E. Ives and Witmer Stone.

To Miss A. Peniston, of Peniston’s, Bermuda, I am under special obligation for the use of much new material illustrating the Bermudian fauna ; and Iam similarly indebted to Dr. W. H. Dall, of the U. 8. National Museum, Washington, for having placed at my disposition the collection of Bermuda shells made a few years ago by Mr. G. Brown Goode.

Finally, I desire to convey my thanks to the members of my class—Messrs. J. E. Ives, Witmer Stone, Roberts Le Bou- tillier; Misses Emma Walter, Mary A. Schively, Virginia Maitland, Emily G. Hunt, Ella Hunt—all of whom rendered much valuable assistance either in the field or in the labora- tory.

A. H.

AcapEmy oF Natura Sciencrs, Philadelphia, September, 1889.

CONTENTS.

The Bermuda Islands. (encral Impressions.

The Outer Reef.

Physical History and Geology.

The Coral-Reef Problem. Relationship of the Bermudian Fauna. Zoology of the Bermudas.

Zoology (continued).

Zoology (Arthropoda).

Zoology (Mollusca).

Notes on the Literature of Coral Reefs.

Results of Geological Observations.

PAGE.

97

. 136 . 146

166

. 202

46

Summary of Observations on the Bermudian Fauna 95

CORRECTIONS.

PAGE.

40. For “ perspicuity”’, sixth line from top, read perspicacity.

58. In place of the words * more rapid”, third line from top, substitute greater. 102. For “ pediculate”, eighth line from bottom, read peutcel/ate.

THE BERMUDA ISLANDS.

My first impression of the Bermudas was one of disappoint- ment. I had heard so much of the “hundred islands,” of the luxuriant vegetation, that I found it difficult to realize that these undulating hills, rising in their garb of withered green, were in reality the far-faméd pearl of the Atlantic. But our visit was timed for the month of July, and possibly the withered condition of the vegetation had something to do with this feeling of disappointment. The clumps of palmettos which are bunched against the hillsides were as yet undistinguishable, and the eye rested on a monotonous expanse of dirty green, re- lieved here and there by dark masses of the Bermuda juniper, which, from a distance, recalled the cloud-shadowed patches of our northern mountain slopes. Innumerable particles of white cottages gleamed forth in the bright sunlight, but their uniform brilliancy only served to intensify the sombreness of the background which they illumined.

I had, from assumed geological knowledge, expected to see a long white crest rolling over the outer reef, but in this ex- pectation I was also disappointed. We were being carried in on the flood, and no trace of this natural parting of the waters

2 THE BERMUDA ISLANDS.

was visible. As we approached nearer to the shore, however, abrupt changes in the color of the water revealed the position of the coral-shallows, but we as yet saw nothing of the reef of the imagination. Occasional jelly-fishes floated lazily by, and the ever merry petrels were still quivering in our path of beaten foam. Our first tropic-bird hovered about the rigging, seemingly surprised at the early intrusion which we had per- mitted ourselves. The flying-fishes became more numerous as we neared the islands, and they could be frequently seen skip- ping away five or more at a time, and usually in a direction at right angles to the line of the ship.

I was anxious to determine the true nature of their aerial locomotion, and to settle the vexed question of the supposed flying movements of the fins. We accordingly watched these interesting creatures very intently, and followed them with our glasses over their entire course. So rapid was their motion, however, that it was not easy to keep them within the field of the glass, and still less easy to hold them in distinct vision, and for a long time we really hardly knew what we saw. We failed, however, to detect any positive continuous move- ment on the part of the fins, and it certainly appeared as though in all, or nearly all, cases the animal merely shot forward as the result of some primary impetus, taking a course nearly horizontal with the surface of the water. This direct course, in view of the apparent method of pro- pulsion, was certainly surprising, as it would naturally be expected that from an initial leap the line of travel would be that of a regular curve. But the horizontal course was pos- sibly more apparent than real. At intervals, two or three times in asingle flight, the animal seemed to strike the crest of a wave, and acquire new impetus from a blow of the tail. In this way the flight may be said to be one of distinct passages —although without arrest of movement—in which the curve motion largely disappears, or is at least reduced to its lowest terms. Indeed, the successional character of the flight could be plainly seen in the sudden jerky changes of direction which

GENERAL INPRESSIONS. 3

were marked off at irregular intervals, and at points where rising waves apparently met the supplemental strokes of the tail. The duration of flight was from five to eleven or twelve seconds, while the distance covered was probably, in extreme cases, not less than 200-300 feet, and possibly even more.

The inner waters of the reef showed those remarkable con- trasts of color which have been so frequently dwelt upon and depicted by travelers. From the most intense indigo we pass abruptly to a brilliant emerald, and from this again possibly to a bright sea-green. So sudden are the transitions that the semblance of a natural water is largely destroyed, and for a moment one feels inclined to doubt the reality of the scene before him. I must confess that had I been informed in ad- vance of these wonderful chromatic effects, I should have been loud in pronouncing the impossibility of their occurrence, so wholly unnatural did they appear.

Passing through the line of old hulks, whose. grass-grown bottoms and battered planks emphasized the words of condem- nation which relegated the ancient merchantmen to the rank of objets d’ art, we entered the harbor of Hamilton. The fact of its being Sunday did not obtrude itself upon the throng that had assembled to greet us on our arrival. The helmeted red- coat and servant, custom-house officials and steamship agents were out in force, but they were far outnumbered by that class of easy-going inhabitants whose hardest labor appears to be that of doing nothing. The time-honored custom of building connecting gang-planks instead of bringing the ship close up to the wharf, delayed our debarkation by about a half-hour, but delays of this or a similar kind, as we soon discovered, are of little moment with the Bermudians.

The capital city, Hamilton, has little of interest to detain the stranger beyond the beautiful display of exotic plants which are to be found in the private gardens. The broad and pleas- ant avenues which intersect the town at nearly right angles, and glisten with that intensity of which only a white lime- stone is capable, possess the general features of the ordinary

4 THE BERMUDA ISLANDS.

country roads, setting firm and hard under almost all condi- tions of weather and temperature. They rarely require repair- ing, and their even compactness well sustains the quality for which the Bermudian roads are famous. Rain affects them but little, except in so far as it assists as a solidifier, and a few moments after a heavy shower they are generally as pass- able as after prolonged exposure to the sun. Here and there extensive villas and gardens betray opulence, but more com- monly it is the appearance of pleasurable comfort rather than the possession of riches which appeals to the eye of the visitor. The recessed house-fronts, opening upon broad, shaded veran- das, typifv a style of architecture doubtless best adapted to the requirements of the climate, while the dazzling whiteness of the exteriors emphasizes an amount of attention bestowed upon house-decoration which would prubably surprise even the proverbially neat cottagers of rural Belgium and Holland. We were informed that the operation of whitewashing was re- sorted to as often as twice a year, and where, as is almost uni- versally the case throughout the island group, the drinking water is collected as off-flows from the roof, this part of the house is anointed as well as the sides. At intervals throughout the town, as also in the country, extensive inclined basins have been constructed for the reception of rain-water, and serve as reservoirs for periods of emergency.

The shops are in the main not attractive, and on the whole they betray a lack of energy in their management which is surprising in a region so largely visited by strangers. We were recommended to a presumably fashionable confectioner’s, the floor-space in whose establishment was given up in large part to a display of hats and clothing, and the walls to musical instruments. In another large establishment it was reported that anything could be obtained from a coffin to a pulpit, but we found it impossible to procure an ordinary insect net; nor were we better rewarded as far as this, to us necessary, article was concerned, by inquiry elsewhere.

As before remarked, the attractive feature of the town is to

GENERAL IMPRESSIONS. 5

be found in the display of exotic plants. This exhibit is, how- ever, not confined to Hamilton; it is the property of the entire island group, where it has become, if the expression might be permitted, naturalized. The unfortunate ones among us who in the northern region ecstatically wonder at the rare treats which the floriculturist from time to time lays before them, can obtain but little comfort from a trip to the Bermudas. Their earlier-formed notions of grandeur soon disappear. It would, however, be conveying a false impression to-state that the veg- etation is luxurious, or that it is at all comparable in exuber- ance with the vegetation of the true tropies, or even with that of many parts of the peninsula of Florida. On the contrary, it is on the whole sparse, and only here and there, in favored localities, or wherethe husbandman has largely assisted nature, does it reveal those touches of picturesque quality which so impress the mind of the stranger, and lead him to believe in special luxuriance.

The native arboreal vegetation is scrubby, consisting almost wholly of the Bermuda juniper and the sabal or palmetto, the latter being probably the only native species of palm of the twelve or more forms now found on the islands. The date and cocoa-nut are both cultivated, but it is only exceptionally that the fruit arrives at maturity. Superb specimens of the former, the so-called “three sisters,” are found in the singularly attractive public garden of St. George’s, but elsewhere the tree is not exactly uncommon, rising generally in-solitary grandeur above its less pretentious associates. Nothing, it appears to me, can surpass in majesty the five specimens of cabbage-palm (Oreodo:a oleracea) which adorn the roadside at Pembroke Hall, in the outskirts of Hamilton, and justly constitute the pride of the Bermudians. Like granite monoliths the gray shafts, 60- 70 feet in height, stand unbending to the elements that play about them, unmoved by the force that tosses their delicate plumes into restless activity.

Of our common deciduous trees, oaks, birches, beeches, pop- lars, etc., there is scarcely a trace to be seen, nor is there any-

6 THE BERMUDA ISLANDS.

thing to replace them. An occasional sycamore, mulberry or weeping-willow still reminds one of the temperate north, but beyond these and the Bermuda juniper, there is little sugges- tive of the woods barely six hundred miles distant. The uni- versality of the juniper, however, imparts a decidedly north- ern aspect to the vegetation, despite the large number of tropi- cal elements that are embodied in it. The latter are too irregularly scattered to constitute dominating factors in the modeling of thelandscape. At intervals bits of delicious tropi- cal nature surprise one; warm and sunshiny patches of palm- land, largely overgrown with the coarse bracken, and bordered by almost impenetrable thickets of banana and plantain, fall refreshingly upon the eye that has perhaps become satiated with the juniper, and that glory of the Bermudas, the oleander. O’er hill and dale, far and near, in the garden and along the roadside, this superb bush szatters its fragrance to the winds. For one who has not seen the rose-flowered oleander in its na- tive home, or in this land of its adoption, it is impossible to conceive of the effect which is produced by the great masses of showy blossoms which appear here, there, and everywhere throughout the landscape. The hedges are ablaze with their blossoms, and buried in perfume; the roadways are simi- larly bejeweled and scented. I can only compare the general effect with that produced by our copses of rhododendron, but, while the flowers and foliage of the oleander suffer as indivi- ual elements in the comparison, they more than compensate by their masses.

A first impression of a country drive in the Bermudas, along some such road as the “middle road” leading from Hamilton to Flatts Village, is not soon forgotten. The gray, one might almost say omnipresent, bounding wall, which forms part of the natural rock of the islands, the retired and sheltered cottages, the peculiar inhabitants—more black than white—and above all the vegetation, strike one as strange and novel. Birds of bright plumage, the red cardinal and blue-bird, flit numerously before you, and although they are regular

GENERAL IMPRESSIONS. 7

members of the North American avifauna as well, they ap- pear here in a different light than with us, since they, with the little ground-dove, form the most noticeable, if not the domi- nating, elements in the bird-fauna of the islands. We are in a little world of our own, distinct from either Europe or America.

The corn-fields of our temperate north are here largely re- placed by fields of bananas and plantains, which are grown in dense and almost impenetrable thickets. Although at first at- tractive by their novel, and suggestively tropical appearance, the eye soon wearies of the gross and wind-rifted leaves, and eagerly falls upon the much more delicate vegetation of the bamboo, which here and there shoots its willowy tufts 30 or 40 feet into the air. The cane is also a graceful ornament about many of the country cottages.

The banana “trees” were laden with fruit at the time of our visit, and naturally we had a good opportunity to judge of the merits of this highly-prized article of food with the Bermu- dians. At breakfast, dinner, and supper it was a constant accompaniment of the table, and always welcome. The fruit is considerably smaller than the imported article with us, and decidedly tastier or sweeter, doubtless due to its being picked fresh from the plant. The more commonly cultivated variety is the form known as Musa Cavendishi, or dwarf banana, which rarely exceeds, to the bend or apex of the leaf, more than about eight feet in height; it always presents a stubby appear- ance, more like a great coarse weed, which has grown up spontaneously, than a cultivated plant. Indeed, it can scarcely be said to be under cultivation, sinve practically no attention is paid to its proper growth and development; nature does it all. Bunches of fruit weighing fifty pounds or more are no rarity, and occasionally they reach nearly double this weight.

The plantain, which is more rarely seen, and whose fruit is not held in popular favor as an article of food, isa much more graceful and imposing plant, with leaves eight or ten feet, or even more, in length. It grows to more than twice the

8 THE BERMUDA ISLANDS.

height of the common banana, and, although its leaves are largely wind-rifted, it never presents the shabby appearance of the latter.

Among the other distinctive accompaniments of the road- side are the aloe and yucca, or Spanish bayonet. The flowering stems of the former, rising twenty or twenty-five feet in height, are not an uncommon feature in the landscape of the garden- tracts. Of the fifteen or more species of cactus now found on the islands, some of which, like the Turk’s cap, or melon cac- tus, and the night-blooming cereus, are extensively cultivated in the gardens, only one, the prickly-pear (Opuntia vulgaris), can be said to be at all common. It is found scattered here aud there about the sandy wastes, or hanging in sprawling masses from the road walls. Some notion of the luxuriance of growth may be had from the condition of the plants of the night-blooming cereus. Shortly before our departure from the islands we were hospitably invited to visit a plant of this species in the garden of a Mrs. Peniston, just outside of Flatts Village. It is scarcely necessary to say that we were surprised when we beheld a plant covering an area equal to that of a fair- sized room, and supporting upwards of 200 of the most superb flowers! Well may the tourist go back down-hearted to his

native conservatory. But this is not the only instance where a comparison be-

tween home and foreign products may give rise to sad reflec- tions. Alas, how sadly changed must be the conception of a rubber-plant, after one, who had hitherto been accustomed only to the “ wonders” of the drawing-room and conservatory, has seen the monster, stretching forth its arms like an oak, at “ Par le Ville,” Hamilton !

If, however, the eye is riveted to these remarkable forms of vegetality, it meets only with disappointment when it scans the usually sparse herbaceous vegetation of the woodlands, or that which covers the open meadows and rock-surfaces. We look in vain for that rich, dense green which forms the sunny undergrowth of our forests, for the crop of weed and grass which

GENERAL IMPRESSIONS. 9

is the wealth of our fields and pastures. Plenty of grasses there are, it is true, but they are in most places thin and weak. Only here and there in the deep and open hollows, as in the neighborhood of the “marshes,” do they show anything like luxuriance of growth. It should, however, be stated that in many sheltered limestone hollows, as well as along similarly protected rock-ledges, the vegetation is wonderfully profuse, interwoven and intermatted so as to render penetration almost impossible. The coffee-tree thicket back of Joyce’s cave, and the convolvulus cave close by, are wonderful exhibitions of this kind; and likewise the tract about Walsingham. But over the greater part of the island one may sing his peans to the sage (Lantana), which has virtually taken possession of the soil, a not very attractive nor delightfully odorous plant.

Our headquarters during our brief stay at the Bermudas were at the Flatts Village, a small assortment of neat houses and cottages situated at the entrance to Harrington Sound. A strong current passes here at high-water into the inner basin, bringing in much sediment from the open sea, and with ita rich assortment of animal life. Thelow-water sands constitute one of the best collecting grounds of the archipelago, excepting, of course, the outer reefs, and the under surface of almost every

_ stone offered something for our collections. We were fortunate to discover here a new species of cuttle-fish (Octopus chromatus) characterized by unusually attenuated tentacles; but, beyond two other individuals of another species which we failed to ob- tain, this was the only representative of this order of animals with which we came in contact during the entirejourney. Yet, they are said to be specially abundant just among the rock crevices of Flatts Inlet.

It is wonderful with what tenacity these animals hold on to their anchorages when a forcible attempt is made to eject them from their shelters. We in vain tried by both coaxing and pulling to dislodge one of these interesting creatures, but, de- spite the havoc made by chopping the enveloping rock, we

10 THE BERMUDA ISLANDS.

were compelled to desist from our attempt after the labor of a full hour and a half. The chromatic changes of the skin were at. times very rapid, and so nicely did the animal adjust its color to that of the rock as to render its outline barely visible.

The wonderful transparency of the greenish waters permitted objects to be distinctly visible at depths of 20-25 feet, and where there were no moving ripples, at even greater depths. I doubt much, however, the statement that under ordinarily favorable conditions objects may be distinguished at depths of 60 to 70 feet, even with the aid of the water-glass ; at any rate, our own experience failed to give support to this commonly- received notion. Almost everywhere within the bounding reef, except where special circumstances have favored the de- velopment of coral and millepore patches, the bottom is largely barren, presenting a nearly uniform expanse of coral sand. This is the paradise of the sea-urchin (Toxopneustes variegatus) and of the great black sea-cucumber which is so common in the inner waters. From the anchorage of the Villa Frascati we watched day after day the uncouth ebony masses of the latter, scattered like so many black blotches over the sand. Only ex- ceptionally could they be observed to change their position, although the rolls of sand drawn over the surface indicated that such changes were not uncommon; not improbably their perambulations take place largely at night-time, when their movements would not be likely to attract attention. In the normal condition of rest and apparent non-anitality the creat- ure might readily pass aggressive observation, even though it be the most conspicuous object on the bottom; and in thus deceiving what might otherwise be formidable enemies it is probably largely assisted by its forbidding black color. It is a significant fact, although it may hold no special relation in the matter, that another form of holothurian (like the latter, new to science), of almost equal size, and with a ground color of reddish-yellow, occupies the same haunts, but in vastly di- minished numbers. Can it be that it is suffering extermina- tion through the possession of a more attractive, even though less apparent, coloration ?

GENERAL IMPRESSIONS. 11

Some of the pleasantest of our leisure hours in the Bermudas were passed in gazing into the kaleidoscopic waters which bathe the gardens of the Villa Frascati, and who that has once glanced into this liquid glass can forget the picture that is there presented? A giant palette dipped beneath the water. We have the same bright smudges of cardinal and Jemon-yellow, the streaks of green and blue, the purples, oranges, and blacks —in short, all that brilliancy and wealth of color which belong to the painter’s upper row. A species of encrusting sponge, possibly a Microscionia, made large patches of the brightest red on some of the detached rock, while immediately alongside, another sponge formed clumps of equally brilliant yellow, and still another, lesser patches of green. This violent contrast of color, which is still farther intensified by the whiteness of the supporting coral sand, is kept in a pure key. There is no dis- cord, and not very much more true harmony ; it is strongly marked individuality. If any one still doubted that ocean water had a natural color of its own, a single glance at the flowing emerald would have been sufficient to dispel all doubts in the matter.

The most beautiful of the inner waters of the archipelago is Harrington Sound, an almost closed lagoon which extends for about three miles eastward from Flatts Village. Its only open communication with the sea is by way of I latts Inlet, the extreme contraction of which compels the water to flow in and out with the fury of a mill-race. We did much of our dredg- ing here, but scarcely met with that success which we had anticipated. The bottom is manifestly largely a sand-barren, and in a general sense unproductive. We, however, picked up specimens of a beautiful new species of Chromodoris, and quantities of a remarkably crassiform Chama. The latter more nearly approaches a fossil from the Pliocene deposits of Florida than any other species with which I am acquainted. Along the borders of the Sound the coral-growth, consisting mainly of Isophyllia, Oculina and Siderastreea, is largely developed, but we everywhere failed to detect traces of the

12 THE BERMUDA ISLANDS.

large meandrineform types which form such a prominent feature in the life of Castle Harbor. In the latter, again, the Tsophyllias were largely wanting. Probably upon the much greater depth of water in Harrington Sound, and the ¢ absence of a submarine platform, is dependent mainly the difference in the coral life of the two almost contiguous bodies of water.

It is difficult to conceive of a more beautiful and refreshing sight than that which is presented by the sheltered coral pools, with their wealth of color, which bite here and there beneath the crumbling banks. Corals, millepores, and stone-encrusting Alge vie with each other in building up the common domain, whose most intricate details are revealed by the transparency of the waters. Even the tiny polyps may be seen expanding their delicate crowns of tentacles. What a charming vision of the busy life about us! The sea-anemones are especially abundant in these rock-shelters, and some of them are strik- ingly beautiful; but on the whole they are less brilliantly colored than those of our northern shelters. Among the corals, some of the species of Isophyllia were the most highly colored, the browns and greens being remarkably rich. Below a depth of a comparatively few feet coral-life largely disappeared, and along the actual floor of the Sound, say at depths of from six to eight fathoms, we only obtained Oculina. No haul of over ten fathoms ever brought up a coral.

During much of our stay on the Sound the water was very rough, and its inroads upon the bordering cliffs and crags were painfully manifest. The Sound is now actually making, and without question it has been in this condition of self-formation for a long time past. The ledges, islands, and isolated rocks all speak of destruction, and of the former occupancy of the basin by dry land. At the present time the general depth of the Sound may be taken at about 45 to 60 feet, although our line frequently sounded 12 fathoms; the greatest measurement was made in what is known as the Devil’s Hole opposite Peniston Point, where the line ran out 14 fathoms. I was informed, however, by the American Consul, the late Mr. Allen,

GENERAL IMPRESSIONS. 13

that soundings had been obtained in the same place of 16 fathoms. The dredge-net usually brought up from these greater depths only a grayish-white mud or ooze, largely made up of coral and coralline fragments and the debris of the crumbling cliffs. among which the perfectly formed tests of a limited number of Foraininfera—Globigerina, Orbiculina— could be made out. A deposit is manifestly accumulating on the floor of the Sound, and at a rate evidently much more rapid than that which marks disappearance through solution.

Our journeyings through the country were largely made by cart, a ramshackle two-wheeled arrangement which we canopied so as to protect us from the force of the sun’s rays. That a party of nine, men and women closely huddled together, with an arrangement for traveling such as we had, should’ have at- tracted some little attention, or even drawn out the smiles of the kindly-disposed natives, goes without saying. We found it impossible at the Flatts to obtain a two-horse conveyance of any description, consequently we were compelled to put up with a simple cart, or with that in combination with another vehicle. Fortunately, the excellent condition of- the country roads ren- dered traveling even in our rude contrivance fairly comtortable, while the load was not over burdensome to the single animal. The statement that has gained currency that two-horse con- veyances are practically unknown in the Bermudas has noth- ing to support it.

We did not suffer so much from the glare of the roads as we had anticipated. The anticipatory warnings concerning green - umbrellas and black-goggles had succeeded in thrusting these articles of defense upon us, but they were barely more needed here than in any other limestone region. Nor did we find the heat of the sun to be of that oppressive quality which report madeit. The highest marking of the thermometer during our sojourn (July) was 84° F., considerably lower than what we should have expected, during the same season of the year, for the region about Philadelphia or New York. We found but little difference between the temperature of night and day—

14 THE BERMUDA ISLANDS.

some four or five degrees—and usually the early hours of morn- ing were the most oppressive. At that tine the atmosphere is more settled, and in a measure lacking in those refreshing breezes which make the climate, despite the heaviness which a moisture-laden atmosphere brings with it, pleasantly bearable. Except in localities where you are temporarily debarred from the benefits of the breezes, the heat isin no way oppressive, and on the open waters we found that the difficult work of dredge- hauling could be done without special fatigue, and without drawing perspiration. Indeed, this work was not nearly as trying as I found it two years before in the waters of Nantucket Island. The balmy air of evening and the later hours is de- licious, and permits of a night being passed in the open air without discomfort. Only from sudden showers is any annoy- ance to be anticipated. These, however, are sometimes very sudden, and seemingly the rain falls at times when it would be least expected. It was a common saying with us that a clouded sky could be relied upon, whereas: the opposite was threatening. The passing off of a shower is, however, just as rapid as its beginning, and often the whole rain was over in a few seconds. Only once did we experience a lasting furious rain, but then the water descended in torrents. But within an hour after the close even of this rain the roads were practically dry.

IT.

THE NORTH ROCK.

In the open ocean, north of Flatts Village, lies a cluster of rocks upov which the foot of man has thus far but rarely trod. Gray and weather-beaten, they are yet firm as of old, and bear well the marks that a struggle with the sea has impressed upon them. During some six hours of the day these isolated rock pinnacles, of which the largest barely exceeds the double- height of man, are united to one another by a species of or- ganic or living basement, while during the remaining hours they are immersed in the blue coralline sea by which they are everywhere surrounded. Nine miles distant lies Bermuda— or more properly, the hundred or more islands and islets which together constitute the Bermudas—a soft line of purple stretched against the southern sky. To the southwest the eye detects the white shaft of Gibb’s Hill Light, a giant pillar cap- ping one of Bermuda’s greatest elevations—245 feet—while to the southeast the pharos of St. David’s, the all-guardian of the archipelago, plays hide-and-seek with the foot-hills that nestle at its base. Beyond is all sea—the green-blue ocean in whose bosom are locked the treasures of an unseen world.

This fragment of a universe is practically all that is to be seen of the great outer reef, which lies buried, even at low water, at some little depth beneath the surface. The distance from the main-land renders access to it difficult, and it is only under exceptionally favorable conditions of water that it can be approached with advantage. Even after the surrounding shallows have been crossed it is not yet easy to effect a landing,

16 THE BERMUDA ISLANDS.

and we found that our pilot was little inclined to risk his boat in the ragged growth of millepore and serpula which every- where forms the superficial portion of the growing reef. This inaccessibility, doubtless, accounts for the fact that so few among the visitors to these distant shores—or for that matter, even residents—have visited this remarkable spot, which is, be- yond comparison, the most interesting feature which the Ber- mudas have to offer. To those who have seen the reef merely by sailing over it, it can be well said that they have but half seen it—they have missed its greatest charms.

The traverse of the inner waters between Flatts Village and the reef is of itself replete with interest. Here and there glimpses of the bottom reveal wonders of a natural fairy-land which bid welcome to a realm of indescribable beauty. Corals of bright orange and yellow, sponges of black and cardinal, nodding sea-fans of purple and silver, and fishes of all that brillianey of coloring which distinguishes the ichthyic element of the coralline seas, these and much more are the pictures that appeal invitingly to a habitation in the oceanic waste. The ruffled surface of the water bars out that clear vision to which we are accustomed in our meadow-wanderings, but the magic of a few drops of oil, or the stilling of the water- glass, brings out the relief in the most wondrous detail. The bottom bristles with a forest of rising stems and branches, the work principally of that most indefatigable hydroid-coral, the millepore, and through it are scattered the roses of the deep. Countless black sea-urchins (Diadema) lie quietly nestled in the maze, while here and there, where the animal shrubbery has permitted the white sand to come to view, we catch passing glimpses of the lonely black sea-cucumber (Stichopus diuboli), quiet and motionless, as in the stiller waters of the Sound. One of the most beautiful objects of these waters is the pink tunicate Diazona whose long stems we hooked up in association with one or more forms of Gorgonia.

The water shallows, and we approach the boundaries of the outer reef; the huge brain-corals (Diploria) rise to within four

SVGNWNYEd AHL

oe

THE OUTER REEF. 17

or five feet of our keel, and show their cerebral convolutions with the distinctness of cabinet specimens. But those of us who are accustomed to the white corals of museum-shelves and mantels see nothing of that description here. The internal framework or skeleton is completely covered by the living aninal substance, a thin film of organic jelly of the most brill- iant orange in this instance, from the surface of which protrude the ever-busy polyps. To conceive that these huge blocks everywhere scattered about, three, four and five feet in diameter, should be the silent work of these tiny organisms! But how weak is the conception compared with that which recognizes in the architecture of all the Bermudas principally the labors of the coral animal !

Our launch is now fairly within the reef; we anchor, and take to the whale-boat, determined to storm the little spot that . nature had bequeathed to the ocean wave. We toss gently over the inflowing billows, and at first it would seem as though our enterprise were to terminate in failure. But a moment more, and success is achieved. The lee-side of one of the massive outgrowths of millepore and serpula permits usto enter safely into our little port, and, taking the necessary precautions to land where the solidity of the marginal growth promised security from a too sudden plunge into the sea, we disembark, critics might say, in not very orthodox fashion.

To those who have never seen a growing coral-reef it is impossible to describe the magnificence of the scene. With rapt- urous delight and wonder you gaze through the crystal waters, and follow the infinitude of form: and color that everywhere surrounds you. The eye rests but for a moment on one object, it is immediately called to another. Corals, sponges, squirts, lime-secreting Algze (nullipores) are welded together into one vast wilderness of coloring, a carpet mosaic of the most bizarre pattern and brilliancy. All animal life is out in holiday attire; the crabs, the shells, the worms are painted with the same brush and palette which were used in frescoing the corals and sponges. Red, green, yellow, and purple blotches appear

18 THE BERMUDA ISLANDS.

everywhere, and so finely are they interwoven that the outlines of the elementary parts lose themselves in the body-mass of the whole. Thus has nature provided her weaker offspring with a protective coloring, and allowed them to live almost unobserved amid the haunts of theirenemies. We found the Diadema setosa, the peer of all sea-urchins, very abundant on the reef, where in magnificent contrast to the wealth of color by which it was surrounded, its ebony-black masses stood out in prominent relief from the coral sbelters which itinhabits. All the individ- uals occupied recesses in the coral growth, which they had by some means, probably, managed to keep open. It is a note- worthy fact that while most of the animal forms inhabiting this portion of the growing reef were brilliantly colored, harmonizing with, and shielding one another by, the party-tints that had been culled from the rainbow, these urchins were alone conspicuous by the absence of any such protective cloak; but just in their case no protective guise in the form of coloring is needed, since these animals are abundantly able to shield themselves by means of their greatly attenuated spines. We found three other species of sea-urchin, Echinometra subangu- laris, Hipponoe esculenta, and Cidaris tribuloides, fairly abundaut in the coral shelters, the last-named species, I believe, being now for the first time recorded from the islands.

We secured many specimens of the large Diadema for our collections, but found that caution in handling was necessary, lest the needle- spines would be projected into the flesh, and there broken off in fragments. In what precise manner the animal so deftly manages to insert its spines into the finger tips, and leave them there as reminiscences of its existence I could not determine; but the fact spoke of an occult operation in painful language. The urchins are, however, not the only animals that produce lasting impressions upon the visitor to the reefs. The corals and millepores are all endowed with stinging powers, and the ulcerations and swellings which their nettle- cells produce are frequently retained in quiet discomfort for several days. The jelly-fishes and Medusae are equally dis-

THE OUTER REEF. 19

agreeable in their companionship,’and on two occasions we found that long after stranding, and for hours after life had been apparently extinguished, the Portuguese-man-of-war was still able to discharge with effect its tiny darts, and produce an impressive irritation.

Of the larger jelly-fishes frequenting the neighborhood of the reef we found the pink Aurelia and the rhizostome especially numerous, and it was interesting to watch with what equabil- ity these delicate creatures weathered the rolling billows, how nicely they adjusted their presence so as to evade the breaking water, and kept their pulsating bells in the comparatively quiet zone of only a few inches depth beneath the surface.

The more tranquil pools of the reef are in places stocked with fish, which partake of the same brilliant mould which distinguishes the lower animals. The members of the tribe of labroids, such as the golden “Spanish lady,” the “ blue-fish,” and “hind” were especially conspicuous, darting rapidly from shelter to shelter as our shadows were cast upon the water. Wading through one of these:pools I disturbed the peace of some thirty or forty fishes of the most intense blue and purple, but the rapidity of their movements rendered a determination of the species impossible. We observed, however, none of the lovely angel-fishes, with their long streamers of blue and yel- low, nor any of the parrot-fishes proper, which apparently find a more congenial home in the inner waters of the archipelago.

The surface of the reef that is here exposed above low-water is barely more than a few yards in width, and is everywhere honey-combed into pits of greater or less depth. Many of these pits were dry, or nearly so, while others are permanently filled with water; but whether you examine the one or the other, you find the same traces of a busy animal life. Tiny crabs are especially abundant, and they may be seen scurrying about in all directions; as elsewhere the hermits have well provided themselves, and the moving domiciles of Purpura, Nassa, and Columbella, with their colored patches of algal growth, are con- spicuous objects on the floor of the reef. Seemingly none of the

20 THE BERMUDA ISLANDS.

larger or more conspicuous shells of the archipelago are found here, nor indeed, can it be said that shells of any description are numerous.

The predominant form of coral, at least in the upper layer, is the Porites, whose masses of bright orange appear here and there through the more sombre tints of the serpula by which they are almost everywhere covered. It grows to within a few inches of the water-line, but nowhere did we see it protrude above the surface, even at lowest water. This is true of all the stone-corals with which we came in contact, and also of the millepore. But we found large encrusting patches of that sin- gular actinioid form, Corticifera flava, completely exposed, and beyond the reach of spray. The length of exposure is, how- ever, short, and probably sufficient water is retained during this time within the cavernous mass to minister properly to the wants of the organism.

The serpula grows in dense bunches, forming a true base- ment, which is admirably adapted toward withstanding the at- tacks of the sea. Indeed, everywhere along the border where the surf beats hardest, the serpula growth was most largely de- veloped, and to such an extent as to form a raised rim or har- rier to the more protected inner side. Breaking in on all sides the surf has created a number of more or less irregularly oval islets with depressed centers—or, more properly, with elevated borders—diminutive atolls, as it were; and, indeed, this struct- ure has led naturalists to assume that the form of the true coral atolls, with their central lagoon and bounding outer ring, may have been produced in much the same way, and without the assistance of any such subsidence as was considered neces- sary for their formation by the late Mr. Darwin. I feel satisfied, however, that the two structures, while seemingly alike, have practically little or nothing in common; in the one case the central depression is merely a negative one, being such by reason of a somewhat more rapid growth developed only from the water-line, or within the surf; while in the other, the hollow extends frequently to depths far beyond the zone of

THE OUTER REEF. 21

coral growth, and where, consequently, the building force is entirely removed from the influence of special conditions exist- ing in the superficial layers of the water. We may not yet have fathomed the true method of the formation of coral islands, but such evidences as I was able to obtain at the Bermudas failed to convince me of the erroneousness of the time-honored theory of subsidence which was first formulated by the illus- trious Darwin, and which has so long ministered to the wants of the geologist, and still more failed to satisfy me with the de- mands of the younger school of geologists, who, under the lead of the venerable Duke of Argyll, have pinned to their standard the now almost classical motto: “Conspiracy of Silence.”

I could not readily determine to what extent the ocean side of the reef was more profuse in its coral growth than the in- ner side. Seemingly there could not be much difference, for the profusion of the inner life was such as to make it difficult to conceive how it could have been measurably exceeded. Probably in this regard the Bermudas form an exception to the supposed general rule which defines a comparatively barren area immediately back of the surf. Surely, we found nothing of the kind here.

I was also much impressed by the fact that there were here no loose boulders of rock, such as it might have been assumed would be thrown up by the disintegrating force of the breakers. Everything was firm and compact, except along the margins, where the growth of millepore formed veritable, but readily destructible, chevaua-de-frise. Walking on this part is danger- ous, since it is not always easy to determine how strong the growth is, nor how soon one may find his way into one of the numerous water-passages which honeycomb the mass. We had experience of this danger in wading within the millepore shallows of Devonshire Flatts. The absence of coarse debris is, doubtless, in a measure, due to the small extent of land exposed, and to the depth of water which covers the greater part of the reef. A rise in the reef would probaby bring about other conditions—as was manifestly the case formerly—but

22 THE BERMUDA ISLANDS.

even then the solidity and compactness of the growth would render the process of undermining and disruption a slow one. This is also true of the reefs on the south side of the island, the crests of which are serpuloid, while the lee-slopes are fairly covered with large Meandrinas. We but rarely came across a loose block of stone on the beach, and where such was found it could be generally, if not always, identified as the disrupted part of the cliffs upon which the fury of the surf was expended. The examination of the lime-sand of the inner waters only exceptionally showed recognizable coral fragments, although it was very largely composed of the debris of the more friable millepore. Indeed, it might be said that the sand is properly a shell and millepore sand, rather than one of coral formation, and this is also true in a measure of the cliff-sand of the main body of the islands.

We passed the better part of three hours on the reef, but by the end of this time the water was gaining upon the spot rapidly. In a few short hours the reef would again be entirely covered, save the three gray pinnacles which constitute the lone North Rock.

II.

THE PHYSICAL HISTORY AND GEOLOGY OF THE BERMUDA ISLANDS.

The reefs, islands, and lagoons which together constitute the Somers Archipelago cover an elliptical area, bearing somewhat east of northeast, of about 220 square miles, of which by far the greater part is occupied by water. The land portion is confined almost wholly to the south and southeast, where it makes a broken irregular crescent, some fifteen miles in length, and from one to three miles in width. Five principal islands, of which the largest, with nearly 10,000 acres, contains approximately three-quarters of the entire land surface exposed within the archipelago, are the components of this crescent, about which are scattered some two hundred or more islets and isolated rock-pinnacles. The great body of water or lagoon, as it is sometimes called, which lies north of this chain of islands, and is in direct communica- tion with the open sea, is in a measure delimited by the ellipse of the outer reef, which is wholly submerged even at low water, except at two or three points, the most conspicuous of which is at the North Rock.

The depth of water in this outer lagoon is, in general, about 40-50 feet, although, exceptionally, our sounding-line dropped to 10 or 11 fathoms. For some little distance before the outer reef is reached the water shallows to 20-30 feet, and at various spots within the open, serpula and mille- pore growths rise to within a foot or so of the surface, or even completely up to it, forming irregular oval patches, which can be distinguished even at a distance by the discolor- ation of the waters.

24 THE BERMUDA ISLANDS.

An open continuation of this outer water is the Great Sound, which is to an extent land-locked by the “hook” of Main Island, and its disrupted continuation, Somerset and Ireland Islands. At the eastern end of the archipelago an incursion of the southern waters has formed, or helped to form, the lagoon known as Castle Harbor, an extensive body of water, with a depth of from 30 to 40 feet, whose oceanic boundaries are well seen in Cooper’s, Castle and Nonsuch Islands, and their dissociated fragments. Castle Harbor stands also in direct communication with the northern waters by means of one or more channels, known as “The Reaches,” whi¢h are in part largely silted and coral-grown, and consequently difficult of passage.

Harrington Sound, which bites into the Main Island alone, is the most nearly. land-locked of the inner waters, and at the same time the deepest water in the archipelago. The average depth is probably not less than nine or ten fathoms, and our line frequently dropped to 12 fathoms. We sounded 14 fathoms in the southern bay opposite the Devil’s Hole, and I was informed that 16 fathoms had been obtained in the same locality. Although two miles in length, and approximately a mile and a half in greatest width, this extensive body of water communicates with the outer sea by a channel not more than 50 feet in width, the Flatts Inlet. The breaking action of the waters, the undermined ledges, and the vertical cliffs all clearly indicate that the Sound is still expanding, and it is merely a question of time, if the present conditions continue, when it will be more in the nature of an open bay than of a land-locked lagoon.

The reefs on the south side of the archipelago approach in places to within a hundred yards or as many feet—or even less— of the chain of islands, from which they are separated by a belt of water of no inconsiderable depth, and always existent. They are, therefore, more nearly in the nature of “barrier” than of “ fringing ” reefs, if, indeed, they can be said to strictly belong to either one of these two divisions. Opposite the open

PHYSICAL HISTORY AND GEOLOGY. 25

way communicating with Castle Harbor we sounded nine fathoms in the water back of the reef, and I believe that this depth, or even a considerably greater one, must be found in many places. On the outer side the depth of water increases more rapidly, but not in a degree as to indicate abrupt- ness of descent. The organic growth, which is serpuloid super- ficially, comes to the surface in discontinuous patches, over whose line a white surf may be seen breaking during the greater part of the day. These are the “boilers,” or secondary atolls, as they have been sometimes called.

The outer soundings made by the officers of the “ Challenger” indicate a gradual descent of the bottom for a distance of about a mile, when a much more abrupt slope begins. It is | claimed that within the first belt the average depth does not exceed 12 fathoms, but we sounded 13 fathoms, after making full allowance for slip, at a distance of not more than 300 feet from the breaking surf. Our facilities, however, did not per- mit us to make extended observations in this direction, nor was the condition of the water, when we crossed over the reef, favorable for such observations. Ata point seven miles from the northern reef the “ Challenger” obtained the extraordinary depth of 12,000 feet, which would give an average descent of slope of one in three, exceeding probably that of any equal slope on the land surface. Drained of its surrounding waters, the Bermudas would, from this side, appear like a stupendous | tower, in comparison with which the principal mountain peaks of the land would, as far as abruptness of slope is con- cerned, sink into insignificance. Yet it would seem that, in a general way, at a distance of ten miles in nearly all directions the depth is only from 9,000 to 13,000 feet, or not more than that which is found at an equal distance off the sub-continental plateau. Twenty miles to the southwest-by-west of the Ber- mudas two submerged banks come to within 20-50 fathoms of the surface, and seemingly represent the continuation of a range of heights of which the Bermudas constitute a section. But not impossibly they are merely the summits of isolated

26 THE BERMUDA ISLANDS.

volcanoes, such as the Bermudas may themselves be; the dis- tance between the two groups is amply sufficient to allow of both of them to slope gradually and independently to their bases without necessitating the assumption of a connecting backbone or ridge. The great depth of water, moreover, which lies at no great distance to the west, and likewise in the east, would seem to offer no support to. the notion of such a sub- merged ridge, which would necessarily have to be of limited extent. Still, the shortness of the line cannot be looked upon as strictly negative evidence, since abbreviated chains with lofty summits are not absolutely unknown, even if they are of exceptional occurrence.

The main islands of the archipelago present approximately identical features. Gently undulating hills, rising sometimes with the symmetry of sugar-cones, alternate with broadly open lowland, and pleasantly diversify the landscape. Along much of the northern shores these elevations gracefully descend to the water-line, where they form long reaches of sand-beach, or terminate in abrupt escarpments, largely undercut, and usually of inconsiderable height. Viewed from an eminence, this succession of undulating hills and dales, or perhaps more properly stated, “ups and downs,” with their inclosed lagoons, projecting promontories, and scattered islands and islets, forms a most captivating picture, whose beauty is further enhanced by the magnificent contrasts of color that are presented. To the geologist the picture immediately suggests a region of sub- mergence, or such as would be formed were the more interior districts of Main Island suddenly depressed beneath the water.

At certain spots, well shown on the northern and southern shores of Harrington Sound, and on the Walsingham tract of Castle Harbor, the water has cut vertical faces from the hill- slopes, and constructed cliffs of majestic and picturesque ap- pearance. The Abbott’s Cliffs of Harrington Sound have an altitude of probably not less than 50 or 60 feet. Along the south shore a long line of almost continuous and imposing cliffs faces the ocean. These receive the full force of the battling

PHYSICAL HISTORY AND GEOLOGY. 27

waters, and are cut and moulded into ragged masses wholly unlike anything that is to be found on the opposite shore. This picture of wild magnificence—the beetling cliffs and dash- ing spray—is a surprise to the stranger who has conceived of the Bermudas only from the north, and wanders over to this side expecting to see the picture with which he is familiar re- peated. Long before the shore is reached the character of the work that is here being accomplished can be judged of from the continuous booming that falls upon the ear. Deep bays, alter- nating with bold and ragged promontories, bite through the cliffs in some places, while at others they are still in course of formation. Just west of Hungary Bay and at the Chequer Board, perhaps the grandest views of destruction are presented, but almost everywhere the picture unfolds itself in much the same detail. We could, however, form no true conception of the destructive power of the sea from the condition of the water at the time of our visit to the islands. In the season of storms, and more particularly during a hurricane, the fury of the waters must be almost irresistible, if we give full credence to the reports of experiences of the inhabitants; and the landmarks that the sea has impressed upon the country leave no room for doubt as to the authenticity of these reports. The natural arches at Tucker’s Town, which are now not even reached by the sea, bear ample testimony to an extent of erosion which is not permitted to the sea in its ordinary condition; and the same is true of the massive cliffs, some 80-90 feet, or more, in height, which constitute the “amphitheatre ” a short distance beyond the arches. Several considerations preclude the prob- ability of these structures having been formed at a time when the relations of the Jand and water were different from what they are now, or that changes of level have taken place since their formation. The evidences of recent encroaches of the sea at these points are clearly visible, while there seems to be noth- ing to indicate a late rise of the land-surface. Still, I must admit that the observable facts at our command were not suf- ficient to warrant usin assuming positively that there was no

28 THE BERMUDA ISLANDS.

such elevation; but the reverse could just as well have been, and more likely was, the case.

The loftiest eminence in all the Bermudas is Sear’s Hill, about a half mile southeast of Flatts Village, which attains the modest height of 260 feet. We verified barometrically the earlier determination of this height. After Sear’s Hill, the highest point is reached in Gibb’s Hill, 245 feet. There are no ponds, springs, nor flowing-bodies of freshwater throughout the archipelago, although at one or two points the water of ° interior collecting pools is only feebly brackish. In a cattle cistern or spring, near Peniston Pond, there was little or no salinity appreciable, although the water did not appeal invit- ingly to the human gustatory sense. The porosity of the rock’ almost immediately absorbs all falling water, and likewise con- ducts the sea-water into the innermost parts of the islands, where it doubtless forms a clearly defined basal zone. Much of it must be drawn by capillarity above sea-level. All attempts to obtain freshwater by means of artesian borings have resulted in failure, by reason of the complete permeation of the oceanic waters. The large interior ponds or lakes, all of which occupy low levels, are necessarily brackish, and they support a fauna distinctive of brackish or salt waters. A fairly large peat-bog oc- cupies the center of Main Island, and apparently marks the site of an ancient, now wholly desiccated, lagoon. The peat is said to extend down to a depth of 40 or 50 feet* below the sea-

‘level, or to about the level of the floor of the great outer water which is inclosed by the northern reef.

The rock of the islands is a granular limestone, which is in most places still sufficiently soft to permit of being cut by a hand-saw. On exposure to rain it hardens through cementa- tion, or deposition of interstitial lime, and may then be con- verted into a tough and very resisting material, which is ad- vantageously used: in the construction of houses. Piles of hand-sawn blocks awaiting induration are a not uncom-

*Rice: Geology of Bermuda, Bull. U. S. National Museum, No. 25, p, 7. On the authority of General Lefroy.

PHYSICAL HISTORY AND GEOLOGY. 29

mon sight along the roadsides. The process of the binding together of the loose particles of debris which are to constitute a rock is sometimes a very rapid one, especially along the water’s edge, and may be followed in its different stages.

The basal rock of the cliffs, especially on the south shore, is in places excessively indurated, and about as resisting as a non-siliceous limestone can well be; when struck with a ham- mer it at times rings with all the intensity of the volcanic ring- ing rocks, and chips off as sharp-edged flakes. The granular structure which is so prominent in the softer rock may be re- - tained, but it sometimes largely or wholly disappears, and the mass appears to be homogeneously compact. The matter of hardness or compactness is, however, not one necessarily depending upon age, since we often find the tougher rock oc- cupying the high level, and-overlying the softer rock below. At other places the two kinds of rock alternate with one another. From the constancy of its occurrence at, or near, the base of the island, the hard suberystalline limestone is locally known as the “ base rock ;” it serves largely, but by no means invariably, to distinguish the old beach formation, and thus to locate the former sea-border. The same rock forms the lower moiety of the three pinnacles of the North Rock.

The constituent particles of the softer limestone are of about the size of a pin’s head, or smaller, among which the debris of shells and millepores are distinctly recognizable. Coral fragments are apparently much less abundant, and, indeed, it was only with difficulty that I determined these at all, except where, at long intervals, fragments of large size were caught up in the mass. Possibly, the finer undefined particles may have been those of corals, whose cellular structure would have readily lent itself to a powdering such as would com- pletely efface determining characters. Still, the fact remains that much, or most, of this rock is made of millepore and shell fragments, and whatever part corals may have taken in its formation, it cannot be considered to be a simple coral rock. The examination of the long stretch of beach which faces the

380 THE BERMUDA ISLANDS.

north side of St. George’s Causeway also failed to show much evidence of coral growth, although shells and millepore frag- ments were packedl in endless quantities; the tests, perfect and imperfect, of the foraminifer genus Orbiculina were also very abundant. I do not wish to be understood as saying that the islands are not really of coral formation; that a coral funda- ment exists, needs no further demonstration than is furnished by the rich growth of Diploria and Meandrina within the reef-waters, and by the coral fragments and masses that are inclosed by the beach formation. I wish merely to emphasize the important part which organisms other than corals have taken toward the shaping and the making of the rocks, especially of the superficial parts which have lent themselves to wind-action.

The true relations of the Bermudian rock were first clearly established by Nelson.* With remarkable sagacity this ob- server read the history of the discordant layers, here horizon- tal, there steeply inclined, now arched in one direction, then in another, which appear in all the sections, and he was not slow to point out that they were the result of wind-drift—mere shifting (calcareous) sands which had been thrown about promiscuously by the winds, and had solidified in layers in the positions where they had been finally dropped. This in- terpretation stands to-day as firmly established as it stood when it was first enunciated upwards of a half century ago. The thin knife-sheets which are so characteristic of this drift- rock build up massive beds, which are thrown together in most irregular confusion—dove-tailed, apparently faulted, lenticulated, and otherwise. No more interesting exposures can be had than the faces of the road-walls, both in the city and in the country, where synclines, anticlines, slopes, and horizontals appear sometimes in the space of a few yards. At other places no bedding, beyond the thin lamination, is apparent, and the whole mass rests concordantly either in straight or undulating lines.

*Trans. Geol. Suc, of London, 2d Ser., vol. v, Part I, pp. 108-128.

PHYSICAL HISTORY AND GEOLOGY. 31

The first process toward the forming of this rock must neces- sarily be the pounding up of the material out of which it is con- structed. Wherever the polyps build close to the surface their habitations are attacked by the surf which they themselves create. The long white line of foam which meets the eye of the observer gazing southward from any eminence, and parts the blue waters of the outer world from the more nearly green within, is but the line of battle between the organic and the inorganic forces. It is here that life asserts her supremacy over the sea, and it is here that the sea maintains her right of domain as an inheritance of prior birth. Blocks of coral and coralline are detached and broken, their parts are rocked to and fro in the withering crest, and ultimately, when the fragments have been sufficiently punished by the sea, they are handed over for further chastisement to the action of the wind. In this way the particles are ground finer and finer, a true sand is formed, and dunes begin to rear their heads above the ocean level. Traveling in the line of the wind the dunes pass on- ward, climb over one another’s backs, and comb the gently flowing crests ; from pigmy hillocks they rise into well-fashioned | knolls, and ultimately stand as the eminences which to-day are the Bermudas. No one who,’on the south shore, has watched the great tongues of moving sand,—the sand glaciers of Tucker’s Town and Elbow Bay, for example—stealthily encroaching upon the hill-tops of the interior, and burying everything, in the manner of the locusts of South Africa, beneath their man- tle of destruction, can have failed to be impressed by the char- acter and the magnitude of the work that is being accomplished. It is truly but the music of the sea and wind, but there is enough of it to turn water into land. It seems, indeed, as though Virgil had divined some such region as this when he de- picted the home of ®olus in the following beautiful lines :—

Here Eolus, in cavern vast,

With holt and barrier fetters fast Rebellious storm and howling blast. They with the rock’s reverberant roar

32 THE BERMUDA ISLANDS.

Chafe blustering round their prison door: He, throned on high, the sceptre sways, Controls their moods, their wrath allays. Break but that sceptre, sea and land, And Heaven’s etherial deep, Before them they would whirl like sand,

And through the void air sweep.

(Conington’s Acneid.)

The wolian or wind-drift character of the Bermuda Islands is everywhere apparent; along the roads, on the hillsides, and in the caves we find the same rock made up of organic par- ticles. The layers or seams, inclining now one way, now in another, point to the different positions into which the sand had been fortuitously cast by the winds, patted down, and built up into a series of superimposed layers. Shells, both marine and terrestrial, have been caught up in the drifts, for we find them now embedded in the rock, and scattered over the most remote corners of the island group. I picked up a fairly large fragment of coral at an elevation of probably not less than 150 feet; and, doubtless, other equally large fragments occur at still greater heights. In regions where freshwater streams abound, the materials of terrestrial destruction are washed into these streams, and by them carried into the sea; geologists have long since recognized the force of the say- ing: “the land-surface is on one grand march to the sea.” But here, where freshwater streams are entirely wanting, and the falling drops are immediately absorbed into the porous soil, the conditions are at least in one sense reversed—the march is in a direction away from the sea. Whither it may ultimately tend cannot be foretold.

It is difficult to conceive that these lovely hills, buried beneath their sombre covering of juniper and sage (Lantana), should have been thus shaped by tlie wind; but the facts are plain in their statement, and leave no loop-hole for the doubting mind. The height of the sand-hills, or dunes, for such they really are, is unusually great for a coral island, and serves to

ROYAL PALMS, PEMBROKE HALL.

PHYSICAL HISTORY AND GEOLOGY. 33

distinguish the Bermudas from other islands having an ap- parently related structure. I fully concur in the suggestion thrown out by Prof. Rice that these accumulations could only have been formed at a time when large areas of reef, and not a simple atoll-ring, were exposed above water-level. At the present day nearly all the sand is formed through the de- struction of the existing land-mass, and not as a product of disintegration derived from the growing reef.

Prof. Rice, in his interesting observations on the geology of Bermuda (loc. cit., pp. 10-13), correctly distinguishes a “ beach ” rock as underlying in many places the drift rock of the shores. He instances as examples of such rock the fossiliferous stratum which appears in the chain of islands stretching across Hamil- ton Harbor, the conglomerate of Stock’s Point, near St. George’s, which rises some twelve feet above the water, the lower bed of Devonshire Bay, and much of the basal, nearly horizontal, strata which appear on the south shore. As char- acteristic of this beach rock, it is said that the beds nearly uni- formly dip seaward, but at a very moderate angle, and that they contain largely of the remains of marine animals (corals and shells). The rock is in most cases very tough and hard, and is largely the correspondent of the base-rock that has already been described.

We also found this beach-rock well developed at many points along the south shore, where it rises some 5-8 feet, or exceptionally more, above the sea-level. The series of nearly horizontal ledges, sharply defined by their position from the highly inclined layers of drift-rock by which they are sur- mounted, or into which they graduate landward, which appear basally at the Chequer Board and at Harris’s Bay well illus- trate the characteristics of the rock. I failed however, to de- tect the uniform seaward slope of this rock which Prof. Rice indicates, nor could I satisfy myself that the presence of marine organic remains in a rock were conclusive for consider- ing the rock to be of beach formation, unless, indeed, sueh re- mains were abundant, or else showed by their positions that

‘

34 THE BERMUDA ISLANDS.

they could only have been placed there through the normal manner of oceanic deposition. It is true that in by far the greater number of cases the rock that can be identified as of beach formation contains, when remains are present at all, only the relicts of marine organisms, and that the drift-rock above or back of it contains only the parts of land mollusks. But Prof. Rice justly remarks that the remains of land organ- isms can be readily washed or drifted into the sea, and there combined with the organisms that are subsequently to enter into the formation of a beach-rock. A mixed faunal element would thus be introduced. But much the same kind of inter- mixture may take place in the land-deposits through the washing or sweeping on high of marine organisms, or their fragments, especially during periods of high storm. Prof. Rice recognizes the possibility of such intermixture, but he at- tributes it all to the action of the wind. It is claimed that only small or light fragments can be swept up by it, and that ‘necessarily only these can be found, under ordinary condi- tions, drifted into the rock. A fragment of the shell of Spondylus weighing 1.8 grammes, a valve of Chama, in- crusted with tubes of serpula, weighing 2.7 grammes, and a fragment of Mycedium, weighing 8.3 grammes, were found by that investigator in the sand-drifts of Tucker’s Town, and these weights or masses are given as values of the carrying power of the wind. This, it appears to me, is doing scant jus- tice to the assistance which the wind receives from the sea. Under ordinary conditions the action of the sea may be confined almost wholly to the line of beach, but it certainly is otherwise during storms. At such times there can be no question that much in the way of organic remains is thrown far within the domain of the drift-rock. The hurling of pebbles and stones along exposed coast-lines is sufficient evi- dence of the capabilities in this direction. We were given graphic accounts of the violence of the waters under excep- tional conditions of storm, and were shown, in the house of the Misses Peniston, at Peniston’s, a position reached by

PHYSICAL HISTORY AND GEOLOGY. 35

volumes of spray which we should have believed impossible, were it not for the absolute reliability of the residents of the house who volunteered the information.

At several points more particularly along the north shore I found marine shells (Lucina, Tellina, etc.) imbedded in unques- tionable drift-rock, and, indeed, it could hardly have been ex- pected that such association should not occur. On the whole, however, these remains were not as abundant as one might have expected to find them. The same is also true in a measure of the occurrence of land-snails. One of the com- monest shells of the lower drift-rock is the large Turbo (Livona) pica, a shell which appears to be very abundant about the coast, but which generally, and perhaps invariably, is cast up with- out the animal. I was unable to find anyone among the local collectors who had seen the animal itself, nor did any member of our party succeed in obtaining an occupied shell. Nelson and Rice both attribute the occurrence of this shell in the drift-rock to transportation by hermit-crabs. I can hardly be- lieve that this is the full explanation. I failed to find any of the shells of the beach inhabited by hermits, and was in this respect less fortunate than Nelson, nor do I know of any her- wit of the islands which would be likely to carry about with it the massive full-grown shell. However, my testimony on this point is purely negative.

J admit with Prof. Rice that it is frequently difficult to distinguish between what is assumed to be beach-rock and the regular drift-rock of the islands, especially when the latter occupies a basal and nearly horizontal position. In many places along the south shore where the beach-rock is exposed in heavy beds it occupies but a limited horizontal space, being succeeded by highly inclined drift-rock, which descends to the water-level. This succession is unexpected, and might lead one to infer that there have been local differential movements on the part of the land. But of course this need not have been, and doubtless was not, the case, since an irregular or indented shore-line undergoing elevation would form features similar

36 THE BERMUDA ISLANDS.

substantially to those which are here presented. That is to say, the raised beach-line would be an interrupted one—continuous possibly along an inner contour, but broken on the outer face, where a low-level beach would mark that portion of the*shore which had last risen. In this way, it is not improbable that much of the interior drifts of the Bermudas will be found to be underlaid by elevated beach-rock, and that a continuity of extent actually exists. It appears to me that geologists have not taken sufficient account of the irregularities in an ascending coast line as factors determining the positions or relative al- titudes to which points of elevation must necessarily attain. They are too ready to interpret the obliquity or inclined posi- tion of marine terraces on the assumption of terrestrial oscilla- tions.

The one fact above all others which immediately appeals to the geologist in the Bermudas is the rapid waste which the islands are undergoing and have undergone for some long past period. Everywhere along the coast we have evidences of this waste; the outer cliffs, the cliffs and ledges of the inner waters, the serially disposed islands and islets, all bear witness to a common annihilating process. Along the south shore the lesson of destruction is presented on the most impressive scale, and it is here that we read most clearly the record of waste which the islands have undergone. The huge cliffs are still being undermined and are still crumbling, but they are merely the remains of a land-mass that at one time projected far be- yond the present coast-line into the sea. Thisis clearly shown by the disposition of the drift-rock of which they are composed, the layers of which in most places decline steeply in the direc- tion of the land, turning their basset edges to the sea. Manifestly, the cliffs are merely the inner halves of dunes, the outer slopes of which have been carried away by the sea. The height of the cliffs indicates dunes of great extent, but it will probably never be told at what point in what is now sea they originated, and how much they have lost through oceanic ero- sion. Not improbably the land at one time projected at least as far southward as the position which is now occupied by the crest of the reef.

PHYSICAL HISTORY AND GEOLOGY. 37

There can be no doubt, it appears to me, as Rein* first clearly demonstrated, that Harrington Sound is not the lagoon of a marginal or secondary atoll, but merely a hole that has been cut out of the land by the sea. I think that every one who has seen the working condition of the water in the Sound, the undercut ledges, the scattered islands and rocks, and above all, the precipitous cliffs, which appear on opposite sides of the water, and show an arrangement of lamination or stratifica- tion similar to that which is observed in the cut cliffs of the south shore, must arrive at the same conclusion. The same is manifestly also true of much, if not the greater part, of Cas- tle Harbor, which still retains a sea-ward border in the belt of disrupted land which forms Castle Point, and Castle, Goat, Nonsuch, and Cooper’s Islands. The widening or expansion of this body of water presents itself vividly to the eye of the observer stationed on an eminence, such as that of St. David, whence the field of vision takes in the patches of separating and separated land which are awaiting the hour of their destruction.

Along the borders of Castle Harbor—at least as far. as we observed it on the west and south—there is a broad flat ledge, over which the depth of water is only from about six to ten feet; beyond this there is an abrupt drop into the deeper parts of the lagoon. This feature is frequently found in the true atoll-lagoons, where it forms a shore platform similar to that which is formed around the outer surfaces of sea-cliffs. In how far this ledge may represent a simple coral outgrowth from the shore, or determine a measure of subsidence, can- not well be ascertained. Large numbers of giant brain-corals (Meeandrina and Diploria), measuring three, four, and five feet in diameter, are scattered over it, and form a series of stepping stones in the water. Many of them grow on and over the edge of the platform, so that the latter overhangs in some places. These corals appear to be absent, or at least

* Bericht Senckenberg. Naturf. Gesellsch., 1870, p. 153.

38 THE BERMUDA ISLANDS.

largely wanting, in the deeper waters. We sounded at various points in 5-6 fathoms, and whether this represents a general depth or not, it is certain that the basin is far shallower than that of Harrington Sound.

In the pinnacles of the North Rock we have probably the most imposing lesson touching upon the annihilation of the land-mass. The lower portion of these rocks is, I believe, un- questionably of beach formation; I failed to detect in it the fossils (Cypreeas, etc.) which Rein asserts are to be found there, but possibly my search was not sufficiently systematic to bring them to light. This basal portion of the rock is exceedingly tough and compact, and rings loudly when struck with a ham- mer. The upper moiety is made up of distinctly laminated or stratified drift-rock, which dips at a steep angle. Manifestly, the materials of this ceolian formation must have had some starting ground, and could not have been developed from the small area which is exposed at low water about the base of the pinnacles: The height to which the well-indurated drift at- tains, some twelve feet or more, taken in conjunction with the vertical reduction which the rock must necessarily have under- gone, and the destruction which has ensued elsewhere, argues almost overwhelmingly for considering these fragments to be merely the remains of a land-mass which had at one time very considerable extent, and not improbably actually united with the main islands. The work of destruction, according to this interpretation, may have wiped from existence a piece of terri- tory possibly not inferior in area to that which is now exposed above water.

In view of the rapid destruction which the islands are under- going it remains to inquire what are or were the special condi- tions which have permitted this destruction |to take place, and have so completely reversed the history of the archipelago. For evidently the conditions under which the islands were first built up, and which permitted them to acquire their full development, must have been very different from those which

PHYSICAL HISTORY AND GEOLOGY. 39

are to-day bringing about only annihilation. In order to trace these changes it is first necessary to determine in how far the present outline or area of the Bermudas is a permanent one, or in how far it may have varied during the period of its exist- ence. By geologists, generally, the island group is considered to represent the disrupted parts of an atoll-ring, most of which (as is seen in the northern reef) now lies submerged beneath the water. This is the view which is upheld by Dana in his “Corals and Coral Islands” (p. 218) and by the late Sir Wyville Thomson in his work on “The Atlantic.” The latter states* that the character of the Bermuda atoll “is much the same as that of like reefs in the Pacific, with certain peculiari- ties depending upon the circumstance that it is the coral island farthest from the equator, almost on the limit of the region of reef-building corals.” ‘The atoll character of the island group is also conceded by Prof. Rice, but this authority carefully distinguishes between the present outlines and those which belonged to the original atoll; he recognizes movements of elevation and subsidence, which have practically obliterated the normal form of the atoll, and have left it in a con- dition where there need be no necessary correspondence exist- ing between the present land-masses, with the submerged reef, and the primary atoll-ring. The condition is thus stated by him: “The series of movements required to account for the main features of Bermudian geology seems to be the following: 1. A subsidence, in which the original nucleus of the islands disappeared beneath the sea, the characteristic atoll form was produced, and the now elevated beach-rock was de- posited. 2. An elevation, in which the great lagoon and the various minor lagoons were converted into dry land, and the vast accumulations of wind-blown sand were formed, which now constitute the most striking peculiarity of the islands. 3. A subsidence, in which the soft drift-rock around the shores suffered extensive marine erosion, and the shore platform and

*Op. cit., I, p. 802.

40 THE BERMUDA ISLANDS.

cliffs already described were formed.' With this conception the atoll practically disappears, since, in the absence of atoll characters, there is nothing to indicate that the structure was ever present; at any rate, its existence is rendered purely hypothetical.

Darwin discusses the subject with his usual perspicuity, and finds reason to doubt that the islands are a true atoll. He points out their close general resemblance to an atoll, but in- dicates the following important differences: “ first, in the mar- gin of the reef not forming a flat, solid surface, laid bare at low water, and regularly bounding the internal space of shal- low water or lagoon; secondly, in the ‘border of gradually shoaling water, nearly a mile and a half in width, which sur- rounds the entire outside of the reef; and thirdly, in the size, height, and extraordinary form of the islands, which present little resemblance to the long, narrow, simple islets, seldom ex- ceeding half a mile in breadth, which surmount the annular reefs of almost all the atolls in the Indian and Pacific oceans.” The great height of the land, as compared with other islands, is also commented upon.? |

In all these characters the Bermudas unquestionably dif- fer from a typical atoll, but allowing for the conditions which Prof. Rice suggests these differences lose much of their signifi- cance. They are not antagonistic to the notion of an overdone atoll which is now undergoing destruction. But it is difficult, if not impossible, to demonstrate the atoll condition itself. If itever existed it has been completely masked by overgrowth, for I believe the facts such as they are show with sufficient clearness that the present islands and reefs have little or noth- ing in common, beyond occupying position, with a pre-existent ring. Matthew Jones has well argued’ that a bodily uplift of

1 Geol. of Bermuda. Bull. U. S. National Museum, No. 25, pp. 16-17. 2 Structure and Distribution of Coral Reefs, 1842, p. 204. 3 Nature, Aug. 1, 1872.

PHYSICAL HISTORY AND GEOLOGY. 41

some 50 or 60 feet would lay dry practically the whole archi- pelago, as far as the great northern reef. That such a condi- tion of elevation at one time existed is, I believe, all but de- monstrable; and if this is true the present condition can only be accounted for on one or two hypotheses: simple erosion or erosion in combination with subsidence. The vast amount of erosion that has taken place has already been referred to, and it is barely necessary to enter further into its details. It will immediately suggest itself to the inquiring mind that this ero- sion could not well have taken place without subsidence, other- wise it would be difficult to conceive, except under a condition of very rapid elevation, how material could have initially ac- cumulated, so as to'lend itself to.destruction afterward. To assume rapid elevation, followed by a period of stability when destruction would exceed construction, requires the formula- tion of causes which are not less difficult to receive than those which would explain subsidence. Unquestionable evidences of subsidence are, however, by no means wanting, and coincident- ally they point to an amount of movement which would account approximately for the depth of the great lagoon. Thus, in the excavations made on Ireland Island for the lodgement of the great floating dock, a deposit of peat,* and vegetable soil contain - ing stumps of cedar in a vertical position, together with other vegetable remains, and shells of the common sub-fossil land- - snail of the islands, were found at a depth beneath the water of some 45 to 50 feet. The depth of the peat-bog which occu- pies the central part of Main Island, has already been noticed. It seems to be a not uncommon occurrence, as we were in- formed by the keeper of the light at St. David’s, that stumps and roots of cedars are drawn up by the anchor chains of ves- sels riding in the waters about St. George’s.

The caves of Bermuda afford equally conclusive evidence of subsidence. Many of these now occupy a level considerably below that of the sea, and consequently receive a large in-

*Thomson: ‘The Atlantic,” I, p. 320.

42 THE BERMUDA ISLANDS.

draught of water from that source. In the very beautiful Island Cave, near Joyce’s Dock, on the north shore, the interior pool has a depth of probably upwards of twenty feet-—we were in- formed that it was thirty feet—yet through it rose a ponderous stalagmite, several feet in thickness. Manifestly, this stalag- mite could only have been formed when the pool was not yet existent or at a time when the floor of the cave was elevated above sea-level. The depth of the pool, then, is a measure of the least possible amount of subsidence, from 20 to 30 feet in the present instance. Much the same condition is presented by some of the other caves. These sea-grottoes are among the most attractive features of the Bermudas, and they would, even in regions far famed -for their caves, attract attention. The principal vaults are of fairly large size, but the connect- ing passages are low and contracted, rendering deep penetra- tion difficult.

These various forms of evidence make clear that there has not only been subsidence, but subsidence on a moderately large scale, and in a comparatively recent (geologically speak- ing) period. Indeed, were we to search for evidence of sub- sidence alone we would not be compelled to go beyond the simple drift-rock, which at so many points dips directly into the sea. To what amount this subsidence may have extended

. cannot in the nature of things be determined, but it appears to have been at least sufficient to account for the depth of water which marks the lagoon and inner sounds. Before this subsidence took place probably the entire area now covered by the Bermudian archipelago, and much more, were dry land, and it was at this time, doubtless, that the great sand dunes were elevated. The prevalence of powerful winds on the south side would tend to elevate this side of the island, while the opposite side, not feeling this influence in any marked degree, would remain comparatively low and flat. In a period of sub- sidence the low side would naturally be the first to succumb to the waters, and would undergo submergence long before the elevated slopes. And this is precisely what appears to have taken place in the Bermudas.

PHYSICAL HISTORY AND GEOLOGY. 43

It becomes an interesting question to ascertain how far elevated above water-line the Bermudas were at the time when they formed a continuous island. The data that are presented for the determination of this problem are mainly of a negative character. But if a subsidence of some 50 or 60 feet can be indicated, and we still have beach-rock on the islands at an elevation of some 12-16 feet, it will be necessarily assumed that the actual uplift above sea-level was at least 60 or 70 feet, unless, indeed, the movement was not a uniform or coincident one for the entire island group. This last assumption seems, however, highly improbable. It may, again, be assumed that the elevated beach-rock was lifted since the period of sub- sidence, and represents the closing movement of the land. Its presence therefore need not argue for elevation beyond that which is indicated by its own highest level, some twelve or fifteen feet. But the relation of this rock to the drift-rock overlying it, and the fact that the latter in so many places drops bodily into the sea, forbid such a conception. The beach-rock is manifestly old, and long antedates the last sub- sidence; and for anything that can be shown to the contrary, it is at least as ancient as the lagoons and sounds, and probably much more ancient. Indeed, there is nothing that could lead one to suppose that it is not the original rock which was formed when the island first came to the surface. Although now exposed on the sea-border, it is really an interior rock, as is proved by the broad band of land which must have been removed from the seaward side of the existing cliffs.

Two questions present themselves at this stage of the inquiry. One of these has been much used of late by the opponents of the Darwinian theory of coral formations, and bears upon the formation of lagoons through aqueous solution. The second considers the amount to which a possibly cavernous condition of the island may have facilitated the work of the erosion, and permitted of the present features having been formed without the aid of subsidence.

44 THE BERMUDA ISLANDS.

No one, it appears to me, who has examined any of the in- ner waters of the archipelago can for a moment suppose that the basins holding these waters could have been formed or kept open through solution of the rock supports. Apart from the special difficulties which the Murray theory carries with it, and which will be found more extensively discussed in the general chapter treating of the formation of coral structures, the facts presented by the Bermudas are such as to im- mediately dispose of the theory in so far as it is made applica- ble to them. ‘The material resulting from rock degradation which finds its way into the waters of the different lagoons vastly exceeds in quantity that which could possibly be re- moved through solution; hence we have the entire floor covered with a thick deposit of ooze, as our dredgings invaria- bly proved, and not an exposure of bare rock as we should ex- pect to find in a basin of solution. Organic material, largely foraminiferal, is also accumulating over the floor, and the sup- . ply of formative material from this source alone is probably fully equal to that which is removed chemically by the waters. The quantity of this basal sediment is so great that during a heavy storm, as was witnessed by Rein and others, the entire water reaching to the outer reef was rendered milky white. As regards the second question, the influence of a cavernous struct- ure upon the erosion of the land, the facts are not readily ap- proached. Mr. Fewkes, in a paper recently published* on the “Origin of the Present Form of the Bermudas,” argues that the existing relations of the archipelago are not necessarily the result of subsidence (although he admits that the evidences of subsidence are unmistakable), but of normal erosion, assisted by the breakages which in one form or another are likely to follow the honeycombing of the rock. Caves or long passages are assumed to penetrate into all parts of the islands, and by their collapse are supposed to furnish the hollows which ulti- mately form the lagoon-basin. This idea is not entirely new, and was already entertained by Rein.

*Proc. Boston Soc, Natural History, 1888, pp. 518 e¢ seg.

PHYSICAL HISTORY AND GEOLOGY. 45

A number of serious objections present themselves to the acceptance of this explanation. The premises are largely, if not almost wholly, of a hypothetical character. That the islands are in a measure undermined there can be no doubt, but there is little, if anything, to show that there have been breakages of the extent which would be required by the theory. Evidences of local disruption are plentiful, such as may be found in almost every region of sinks, but as far as I can see there is nothing to indicate that basins such as Har- rington Sound, Castle Harbor, or the great lagoon could have been formed, or even materially furthered, by disturbances such as the cave-theory calls into existence. The even floors of these basins argue strongly against formation through breakage, as does likewise the horizontality of the beach-rock formation. The absence of all indications of disturbance from the latter is significant. But the broader question can well be asked: How could extensive cave formations, extending 40, 60, or 70 feet beneath the water surface, be brought about without subsidence? Whence would the force of excavation be obtained? The answer might be returned: solution. But there is no more reason to assume special solution in the case of the Bermudas or in other coral islands than in any marine limestone formation.

The difficulty in the problem entirely disappears if we admit subsidence, and, as has already been seen, the positive evidences of subsidence are ample. On no other theory, it appears to me, can the waste of the cliffs on the south shore be explained. The direct evidences of subsidence, moreover, do not come from a single point in the archipelago; they are found from Ireland Island and Hamilton Sound, through the Main Island, to St. George’s. And this being the case, there is every reason to assume that the area which was influenced by move- ments of one kind or another was not restricted to the present patches of exposed land, but extended to the submerged por- tions of the archipelago as well.

46 THE BERMUDA ISLANDS.

As the result of our researches we may express the follow- ing conclusions:

1. The present form of the Bermuda Islands bears no relation to the ring of an atoll, except in so far as the outer boundary may be more or less coincident with the boundaries of an ancient atoll.

2. The existence of an atoll in the present position of the Ber- mudas is not demonstrable.

3. The height of land in the archipelago was formed during a period of elevation, when seemingly the entire archipelago was a connected or continuous piece of land, extending as an oval island to what is now the bounding reef on the north and on the south. It is impossible to determine the absolute amount of elevation above the water, but it appears to have been not less than 70 or 80 feet, and it may have been con- siderably more.

4, The lagoons and sounds were formed duringa period of sub- sidence which followed upon that of elevation, and is seemingly still in progress, or was so until a comparatively recent period. The great degradation of the coast-lime took place at this time. It is impossible to determine the amount of such subsidence, but it was at least 60-70 feet, and not improbably very much more.

It will be seen that these results, so fur as they go, are in ab- solute harmony with the views which Mr. Darwin entertained regarding the structure of these islands. They do not prove the correctness of the Darwinian hypothesis of the formation of coral islands, but they measurably sustain it; on the con- trary, they are largely opposed to the requirements of the sub- stitute theory which has been recently proposed. Elevation and subsidence are both shown to have marked the region in its development, and these conditions are more in consonance with the Darwinian hypothesis than with any other.

PHYSICAL HISTORY AND GEOLOGY. 47

The question as to what form of coral structure the Bermu- das actually are—what constitutes their fundament, and how they were built to their existing level—still remains un- answered, and possibly we,may never be able to answer. But I have thought it worth while to introduce a discussion of the general coral question (the chapter following), as it has a bear- ing on the topic at issue.

IV.

THE CORAL-REEF PROBLEM.

Perhaps no class of phenomena has been so frequently ap- pealed to in evidence of subsidence on a grand scale as that presented in the formation of coral reefs. Scattered freely over a large expanse of the oceanic surface, these structures consti- tute features there as distinctive and prominent as do the mountain masses on the continents. Rising in most cases from a deep sea, and with a limited extent, their presence, as organic accumulations, immediately suggests peculiarities of geological construction which are to be found in no other form of relief. It is an ascertained fact, as has been variously demonstrated that the conditions governing the existence and distribution of reef-building corals (Porites, Diploria, Mean- drina, Madrepora, Tubipora, Fungia, Astreea, etc.) are drawn within narrow limits, and that they are equally of a general and of a special character. Broadly stated these conditions are: A surface temperature of the water never falling below 70° or 68° F.; an absence of muddy sediment ; freedom from contact with freshwaters; the necessity, in some cases, of surf action. Accordingly, we find that reef-structures are practi- cally confined to the warm tropical or subtropical seas, and that they are largely wanting in tracts where exceptional cold currents have wedged a path into the warmer waters, or where, as at the mouths of outflowing streams, there is a free dis- charge of both freshwater and sediment. ‘lo this must be ad- ded the all-important fact that the reef-building corals are con- fined to a superficial zone of the sea not exceeding 100 or 120

THE CORAL-REEF PROBLEM. 49

feet ; beyond this depth we meet only with dead coral. In the case of the Bermudas, and in that of a few other reefs, the temperature of the water has heen known to descend to 66° or even 64° F., but this condition is very exceptional.

One of the most familiar and wide-spread types of coral structure is the atoll, which acquires special development in the waters of the Pacific and Indian oceans. It consists of a more or less irregular ring of living and dead coral, enclosing within its boundaries an internal body of water (lagoon), which in many cases is kept in direct communication with the ex- terior by one or more connecting channels of water; the breaks in the ring corresponding to these passages almost invariably occur on the leeward side of the island. The atoll, although frequently so described, is rarely of a circular form, the outline being very generally elongated and angular. In extent it varies from two to three miles, or less,in length to upwards of 40 or 50 miles; where the dimensions are very small the lagoon may be completely absent, or merely indicated by a dry de- pression. The breadth of the coral ring itself does not usually exceed 1000-1500 feet, or somewhat more than a quarter of a mile. In the general composition of an atoll, the following parts may be recognized : first, an outer platform of coral-rock, more or less exposed at low water, which is the correspondent of the ordinary rock platforms resulting from tidal destruction ; secondly, the beach-line proper, measuring a few feet in height, and consisting of coral sand, calcareous pebbles, and triturated shells; and thirdly, the exposed ring itself with the width as above stated, over which, more especially on the windward side, a luxuriant vegetable growth is developed. The elevation of. this portion of the atoll more commonly does not exceed 10-20 feet, although exceptionally the wind-swept dunes of coral sand attain a much greater height. On some islands, not necessarily atolls, however, as Anegada, one of the West Indies, the drift banks rise to a height of 40 feet, while on the Bermudas they considerably exceed 200 feet, reaching at one point, Sears’ Hill, 260 feet.

50 THE BERMUDA ISLANDS.

On the lagoon side of the ring the shore-platform is very commonly replaced by a gently sloping sand bottom, with or without the formation of a true beach area. Frequently there juts out from the shore a growing reef-platform (upon which the coral growth is fairly profuse), which descends with a vertical or overhanging edge to a second deeper zone of coral life. Over the bottom, which presents a more or less uniform character, coral sand and debris, calcareous pebbles, the tests of various Foraminifera, etc., are extensively distributed, form- ing there a sticky white or bluish paste, much like that which extends for miles beyond the outer border of the forming reef. The depth of the lagoons varies from a few feet to twenty or thirty fathoms, as we find it in many island groups of the Pacific (Paumotu, Gilbert’s Group, Keeling Island, ete.). In the Maldives it exceptionally attains 50 and 60 fathoms.

As reef-building corals cannot long survive exposure to the atmosphere it is manifest that the upper limit of the growing mass will be the actual surface of low-water. In the line of the breakers, or in the shallows just beyond, the coral polyps thrive in their greatest profusion, and the almost end- less variety of their forms, not less than their brilliant color- ing, never fails to arouse the wonder and enthusiasm of the traveler. Prof. Dana thus graphically describes the forming island: “The reef of the coral atoll, as it lies at the surface still uncovered with vegetation, is a platform of coral rock, usually two to four hundred yards wide, and situated so low as to be swept by waves at high tide. The outer edge, directly exposed to the surf, is generally broken into points and jagged inderitations, along which the waters of the resurging wave drive with great force. Though in the midst of the breakers, the edge stands a few inches, and sometimes a foot, above other parts of the platform; the incrusting nullipores cover it with varied tints, and afford protection from the abrading action of the waves. There are usually three to five futhoms water near the margin; and below, over the bottom, which gradually deepens outward, beds of coral are growing pro-

THE CORAL-REEF PROBLEM. 51

fusely among extensive patches of coral sand and fragments. Generally the barren areas much exceed those flourishing with zoophytes, and not infrequently the clusters are scattered like tufts of vegetation in a sandy plain. The growing corals ex- tend up the sloping edge of the reef, nearly to low-tide level. For ten to twenty yards from the margin, the reef is usually very cavernous or pierced with holes or sinuous recesses, a hid- ing place for crabs and shrimps, or a retreat for the Echini, Asterias, sea-aneniones, and mollusks. * * * Further in are occasional pools and basins, alive with all that lives in these strange coral seas.”

This description, which is drawn from the islands of the Pacific, is largely applicable to the condition of the Bermudas. Owing to the peculiar submerged condition of the reef I was unable to determine satisfactorily to what extent a breaking surf was favorable or unfavorable to the growth of corals. At the North Rock, the only accessible point of the outer reef, the millepore growth is very profuse, and large masses of Porites may be picked out from below the capping of serpula. The same condition prevails over the Devonshire Flatts, where the surf dashes over a wilderness of atoll-like islets scattered through the lagoon. But this is not necessarily evidence in favor of advantage derived from the surf, since these seemingly more favored patches are the creators of the surf themselves, and they must have risen before assistance from this direction could have been given them. Their existence seems to prove, however, that the action of the surf is no disadvantage, a con- clusion opposed to that which was reached by Bourne from his careful studies of the Diego Garcia Reef.* Along the inner slope of the reef, immediately receding from what might be called the crest, as well as on both slopes of the serpula- capped southern reef, the coral growth appears in unbounded profusion, presenting a perfect maze of millepores, gorgonias, and brain-stones.

*Proc. Royal Society, XLIII, 1888, pp. 453-55.

52 THE BERMUDA ISLANDS.

There is little or no growth of coral immediately along the south shore, doubtless due to the great quantity of sediment that is constantly being washed off from the cliffs. The rocks of Harrington Sound, on the other hand, are largely fringed with patches of Isophyllia, Siderastraea, and Millepora, while in the deep quieter’ waters, judging from the number of our hauls, Oculina is by no means scarce. Reference has already been made to the vast development of Diploria and Mzan- drina on the projecting platform of Castle Harbor, over which the water is normally in a condition of fair stability. This condition confirms the view expressed by Bourne that the coral growth of the inner waters is much more extensive than is generally stated to be the case. A very large part, however, if, indeed, not the greater part, of the floor of the big lagoon is practically barren.

Although the zone of animal activity in a coral island ceases with the water-line, the actual growth of the island does not stop there, but is continued upward by the mechanical and vegeta- ble forces. The destructive action of the billows carries frag- ments of coral-rock far above the limits of coralline existence, triturating the masses-‘into minute surfaces, and upon this im- provised soil a luxurious vegetation, whose origin lies in the seeds wafted thither by the winds, or deposited by birds, may in course of time spring up. Where the action of the breakers is greatest the coral rock assumes the greatest compactness, since the fragments and particles that are derived from the mechanical wear and tear are here firmly lodged or compacted into the spaces of the otherwise comparatively loose coral structure. On the oceanic side of the island we find shallow water—ranging to several hundred feet—for a distance of between 300 to 1500 feet, beyond which the descent becomes rapid, dropping suddenly to several thousand feet. At a dis- tance of less than three-quarters of a mile from the Island of Clermont Tonnerre, tle lead was run out to a depth of 3,600 feet, and yet no bottom was found; at a distance of seven miles a run of 6,000 feet failed to strike bottom. Off the Cardoo

THE CORAL-REEF PROBLEM. 53

atoll soundings made at a distance of 60 yards from the coast failed to detect bottom at a depth of 1200 feet, and 500 feet out from Whitsunday Island no bottom was found by Beechey at a depth of 1500 feet. Captain Fitzroy found that at a dis- tance of 6,600 feet from the Keeling Island shores the lead did not strike bottom even after having been run out to a length of 7,200 feet. Seven miles to the north-west of the Ber- muda reef, as has already been seen, the depth of water is 2,100 fathoms, but the coast shallows for a considerable dis- tance around the islands. It would thus appear that the pitch of the coral island beneath the ocean is ata very steep angle, sometimes considerably exceeding 45 degrees. Indeed, there are some grounds for concluding that in the deeper parts the faces are nearly vertical, rising like gigantic walls from the oceanic abysses.

In view of the peculiar conditions attending coral growth— the limitation of depth to 100 or 120 feet—the difficulty of ac- counting for the occurrence of coral structures in some of the deepest parts of the sea at once becomes apparent. It had, in- deed, been assumed that coral islands merely occupied the sum- mits of submerged volcanoes, and that their distribution over the deep-sea was simply an indication of the existence, in the region in question, of an equal number of buried volcanic peaks or mountain backs. Recent researches have, however, failed in the majority of cases to detect the presence of such hypothetical buttresses rising to within a few feet of the sur- face, but, on the contrary, tend to show that at least in some instances the actual coral portion of the island descends of itself hundreds, if not thousands, of feet into the ocean.

The genius of the late Mr. Darwin has furnished a theoretical explanation of the phenomenon which, even if it cannot be held to be proved or conclusive, has at least the merit of a strong probability in its favor, and of being in consonance with well-determined geological facts and conditions. This “subsidence” theory, which until recently received the almost unanimous support of geologists, is based upon the evidence of

54 THE BERMUDA ISLANDS.

extensive terrestrial movements, and presupposes the existence of numerous land-masses rising from the deepest water. Around these, under favorable conditions, reef-building and other corals would flourish in abundance, the submerged cone affording a suitable base for the development of the coral animal. The external margin of the coral barrier or buttress, which may be assumed to grow from a possible depth of 120 feet, owing to the invigorating action of the beating surf, and an increased food- supply, would probably rise more rapidly than the inner parts, -whose development would also in a measure be checked by the out-pouring of detrital sediment. A shelving inwardly-slop- ing collar or bank, having a land-nucleus in its center, would thus be produced. In the ring thus forming, whose outer mar- gin, through the breaking and heaping action of the sea, would be lifted somewhat above the general water-level, we have the skeleton of the future atoll. We may now distinguish three elements in its construction: the outer ring or collar of coral, the central nucleus of land, and the encircling body of water which separates the two. —

If at this stage of its formation we conceive the enclosed island to undergo a slow and gradual subsidence the following phenomena may beassumed to present themselves. The outer border of the reef would slowly but steadily build itself up to the level of the water, the growth of the coral colony keeping pace with the gradual sinking of its substratum, provided this be not too rapid. The parts sinking below the line of 120 feet would die out, and their future purpose would be merely to afford a base for the super-structure. The island portion, on the contrary, would sink deeper and deeper, until eventually it might com- pletely disappear. We would then have an outer barrier and an inner lagoon, with probably one or more communicating passages between the latter and the sea cut through the coral growth. ‘This is the typical atoll.

When a reef is separated by a considerable body of water from the adjoining land it is termed a “ barrier” reef, of which two distinct types, the “encircling” and the “linear” barrier

THE CORAL-REEF PROBLEM. 55

reef, are recognized. An encircling barrier reef differs mainly from an atoll in that the assumed subsidence has not been suf- ficient to completely bury the enclosed island, leaving con- sequently, no internal sea, but merely a separating channel ‘formed within the coral boundary. By further subsidence, it is conceived, the encircling reef would be converted into an atoll. When a coral boundary extends for a great distance in a more or less linear direction it is termed a linear reef, or “barrier” reef proper. The great barrier reef off the island of New Caledonia extends in a N. W. and S. E. direction for a dis- tance of upwards of 400 miles, and that of the northeastern coast of Australia has a linear extension, with interruptions of more than 1000 miles. In the case of the latter the width of the intervening strait is in many places between 50 and 60 miles, with a depth of water reaching 350 feet. The reef patches, themselves, even in their broader parts, rarely exceed one or two miles in width.

Besides the three forms of coral structure—atolls, encircling and barrier reefs—which have been assumed to give un- equivocal evidence of subsidence, there is still a fourth type, that of the so-called “fringing” reef, which has generally been considered to afford proof either of terrestrial stability or of actualelevation. These fringing reefs hug the immediate shore line, and may, indeed, be said to represent the incipient stage or starting point whence the other forms of reefs were developed ; by slow subsidence a fringing reef would, on the Darwinian hypothesis, be converted into a barrier reef. F ringing reefs are frequently continued as a series of superimposed terraces above the dry land,—an unequivocal proof of elevation. They rarely, if ever, descend in the water to depths much exceeding 120 feet, and, as might be naturally supposed from their man- ner of formation, are but rarely associated with the other forms of coral reefs.

Applying the Darwinian hypothesis of subsidence to the phenomena of coral structures generally, we may deduce the following: A region of atolls, encircling and barrier reefs is

56 THE BERMUDA ISLANDS.

primarily a region of subsidence—of subsidence now actually taking place, or only recently completed; per contra, regions characterized by fringing reefs are regions either of stability or of slow and gradual upheaval. ‘The greatest area of indicated subsidence is that of the Central Pacific, which has been as- sumed to compass a tract measuring 6000 miles in length and 2000 miles in greatest width. Commencing at the Paumotu group, or the Low Archipelago on the south-east, and extend- ing to the Carolines on the north-west, the coral structures dot at intervals the surface of the sea for a linear distance of 100 degrees of longitude, embracing in this, space several hundred true islands, besides numerous reefs of one form or another. In the Paumotu group alone there are, according to Dana, not less than 80 atolls.

The existence of such an enormous subsidence area as is in- volved in the Darwinian hypothesis is necessarily difficult to realize, and, indeed, numerous apparently valid objections seem to interpose themselves to its full acceptance. It has been shown that within, or immediately on the border of, the sup- posed subsiding area there occur local tracts where fringing reefs take the place of-atolls; and, again, others where raised coral patches or terraces clearly indicate elevation. ‘The coral on some of the Hervey and Friendly islands is stated to oc- cur at a height of 300 feet above sea-level; on the island of Guan, one of the Ladrones, according to Quoy and Gaymard, the coral rock is in places fully 600 feet above the sea. In some island groups, as Hawai, Feejee, etc., coral structures ap- parently indicative of both depression and elevation occur interassociated among the different islands constituting those groups, and the same feature—the interassociation of fringing and barrier reefs with atolls—has been observed hy Semper in the Pelew Archipelago (West Pacific). This condition, together with various concomitant difficulties that lie in the way of the Darwinian hypothesis, has led to the rejection by many naturalists—Semper, Guppy, A. Agassiz, Murray, Geikie, and others—of the subsidence-theory, and to the substitution for

THE CORAL-REEF PROBLEM. 57

it of a theory of simple coral upgrowth, with structural modi- fications as depending principally upon currental action and food-supply.

This theory, like its alternative, presupposes as a first, neces- sary condition of coral growth the existence of a submarine basement within the zone of coral life (1-20 fathoms). Upon this, which may be the buried slope or the summit of a volcano, or merely a bank, the coral animal develops and builds to the surface. Where such a sub-structure does not immediately exist, or rather does not extend to the zone within which reef corals are limited, it is claimed that suitable foundations may be obtained through the building up of submarine volcanoes by the deposition on their summits of organic and other sediments. This would explain the apparent anomaly of coral structures rising from depths vastly exceeding the lower boundaries of coral growth, a condition which to Mr. Darwin necessitated the assumption of subsidence. It is well known that through- out the greater mass of the ocean there is a constant rain or down-pouring of organic particles in the form of the calcareous and siliceous tests of Foraminifera, pteropods, diatoms, etc., much of which goes to form the vast accumulation of white mud (Atlantic or Globigerina ooze) which covers the greater part of the oceanic floor. Manifestly, such an accumulation must eventually acquire great thickness. It is more than doubtful, however, if any very considerable thickness: of such deposit has been built up during the existing period of coral growth, or that an accumulation of this kind has materially aided in building up the sub-cora] buttresses of the deeper seas. The investigations of Mr. Murray, deduced from data obtained by the “Challenger,” indicate that a column of oceanic water of 600 feet depth, with a transverse area of one square mile, contains some 16 tons of suspended organic par- ticles; these, if precipitated to the floor of the sea, would make a deposit rotoo inch in thickness. It has thus far been im- possible to determine the duration of life of the organisms furnishing the organic particles, mainly Foraminifera, and

58 THE BERMUDA ISLANDS.

consequently there is no direct way of ascertaining in what period the tests of a given column of water are replenished. But manifestly, there can be no more rapid accumulation of the calcareous ooze than there is lime-carbonate suspended in the sea; and again, the quantity of lime-carbonate so sus- pended must depend upon the quantity of the formative material contained in the sea—the quantity of lime carried in by the rivers, and any residual or surplus quantity that might be already existing. Now, it would seem from careful obser- vation made on many of the most important rivers of the globe that the quantity of lime carried out by them into the sea annually is about one-sixth that of their suspended sedi- ment, which would cover the sea-bottom, if precipitated at a rate proportional to that of the removal of continental sedi- ment—one foot in 3000 years—to a depth of about ;,,, inch. Assuming that one-half of this amount is used by the Fora- minifera for the construction of their shells, the rest being taken up by the mollusks, corals, etc., then the foraminiferal accumulation from this source would be the ,J,, part of an inch annually, or very nearly the amount that would accumu- late from the droppings contained in the 600-foot column of water, as deduced from Mr. Murray’s determination. At this extremely slow rate of accumulation, it would require a period of 100,000 years to build up the thickness of a single foot! Naturally along coast-lines, where the molluscous animals largely contribute to the general growing mass, and where inor- ganic sedimentation is unusually brisk, the process of upgrowth may be comparatively rapid, especially in the trend of powerful oceanic currents. A condition of this kind seems to obtain along the Floridian coast, and it is not unlikely, as has been suggested by A. Agassiz, that the Florida banks have been built up largely in the manner above described. But the conditions become very different when the oceanic abyss, such as the central Pacific, is substituted for a comparatively shallow coast-line. Indeed, even in the case of the Floridian banks it is doubtful if most. of their upgrowth is not really due to

THE CORAL-REEF PROBLEM. 59

bodily uplift rather than to organic and inorganic accumula- tion, as we have most conclusive evidence of an uplift in the peninsula of Florida in a period at least as late as the Plio- cene. Nor are evidences of a more recent contrary movement wanting in the same region.

It will, however, naturally be urged against this assumption of slow accumulation that the quantity of the salts of lime already contained by the sea is vastly in excess of that which is annually thrown in by the rivers, and that, therefore, the amount of formative material on hand is amply sufficient to meet all the exigencies of a rapid growth. The quantity of calcium actually contained in every cubic mile of sea-water is estimated to be nearly 2,000,000 tons, while that held by an equal volume of river-water is less than 150,000 tons. At the rate of the present carrying capacity of rivers it is calculated that it would require 680,000 years to pour into the ocean an amount of calcium equal to that which is now held by it in solution.* The question here naturally presents itself: To what extent is this surplus quantity of lime drawn upon by the oceanic organisms for the construction of their hard parts or skeletons? It isin the nature of things impossible to give a direct answer to this question, but the following considerations suggest themselves. As far as our knowledge permits us to pass beyond the region of facts, we can but assume that the salinity of the sea is progressive or cumulative, and not the reverse, and that the saline constituents of ocean water are primarily the products of destruction arising from the wear and tear of the land-surface. There seems to be no good rea- son for supposing that the quantity of salts in the sea, and of lime especially, was ever much in excess of what it is to-day, unless it was near the beginning of geological time; on the con- trary, there are some grounds for concluding that this quantity may have been less, and even considerably less. If this con- ception is true, it is manifest that, as far as organic consump-

*Murray: “Structure, Origin, and Distribution of Coral Reefs and Islands.” Nature, Feb. 28, 1889, p. 426; 480,000 years according to Reade.

60 THE BERMUDA ISLANDS.

tion of limé is concerned, there is either existing stability in the sea, or that the different shell-bearing animals remove less -of the formative material for their own purposes than the sea receives from continental erosion. In the calculation before made we have used as a basis merely the quantity of lime-car- bonate carried out in solution by rivers; to this must neces- sarily be added that which is derived directly by the sea through its own breakages—the wear of the coast-line—and the other salts of lime of which no account has been taken. If we double the quantity that has been assumed we will proba- -bly more than cover the available supply; a rate of accumula- tion, therefore, of one foot in 50,000 years would be the result, It is needless to say that such a slow accumulation is hardly compatible with any notion of growth from great depths, and that it is entirely opposed to the view which holds to the formation of giant banks leading up to the zone of coral life.* But in what, it might be asked, lies the direct evidence that giant banks are being built up through organic accumulations? Is it merely the finding of foraminiferal and pteropod ooze on projecting knobs of the ocean bottom? This is not a new con- dition, and it is practically repeated in the Globigerina ooze which covers much of the oceanic floor. It would, indeed, be remarkable if such deposits did not exist, but their presence gives no answer to the possibility of building up giant banks under the conditions which would be considered necessary for the making of coral islands. Noone has more carefully studied, or is better acquainted with, the Florida reefs than Alexander - Agassiz, and perhaps no class of reefs has been more frequently appealed to in the recent discussion of coral structures than . those examined by this authority. We are informed by Mr. Agassiz that these reefs are merely organic growths and ac-

*In evidence of the possible rapid accumulation of a foraminiferal and pteropod deposit, and the building up of submarine banks, Prof. Hickson (Address be- fore British Assoc., Bath, 1888) instances the case of the basal limestone of the elevated reefs of the Solomon Islands, to which attention has been called by Guppy. But manifestly this limestone was formed in shallow water, where the conditions for rapid organic accumulation are almost infinitely more favorable than they are in deep water.

THE CORAL-REEF PROBLEM. 61

cumulations, whose present positions, whether of horizontal or vertical distribution, have practically no connection with re- cent movements either of elevation or depression. “There is practically no evidence that the Florida reef, or any part of the southern peninsula of Florida which has been formed by corals, owes its existence to the effect of elevation ; or that the atolls of. this district, such as those of the Marquesas or of the great Alacran Reef, owe their peculiar structure to subsidence.” On. what evidence, it might be asked, rest these assertions? It may not he easy to prove subsidence in the case of the Marquesas and the Alacran Reef, but I believe it would be equally diffi- cult to prove the reverse proposition—i.¢., that there has been no subsidence. As far as the Florida reefs themselves are concerned; I believe the evidence is all but conclusive that they owe much, if not most, of their existence to uplift, and to uplift within a recent geological period. My own researches in the southern part of the peninsula have demonstrated the existence of Plio- cene deposits in vast horizontal, or nearly horizontal, beds as far south as the Caloosahatchie, and there can be ro question that these deposits, which rise to 10 or 15 feet above the level of the sea, are continued for some distance still further to the south.” The same deposits, moreover, are capped by deposits of Post-Pliocene age, proving that an uplift took place in this region as late as the Post-Pliocene period. Thatthis uplift should not have affected the apex of the peninsula, and even the reefs beyond, seems searcely credible. From what we now know of the structure of the Floridian peninsula it is clear that this portion of the North American continent represents a comparatively old chapter in geological history, and that it has passed through much the same phases of construction as the border area of the Eastern and Southern United States. Its periods of elevation and depression, extending back through the greater portion of the Tertiary epoch, were largely coincident with those of the

4«¢ Three Cruises of the Blake.” I, p. 6]. 1888. : 2 Explorations on the West Coast of Florida and in the Okeechobee Wilder- ness,” 1887. : ‘

62 THE BERMUDA ISLANDS.

regions above indicated, and the movements were with little doubt long sustained, and certainly affected large areas at a time. There is nothing, as far as I can see, to indicate that these movements were confined to what is now dry land; the more natural conclusion is that the axial or plateau uplift ex- tended much beyond the limits of the present peninsula, and as well southward as westward or eastward. The similarity in the geological structure of Yucatan, as it appears from our pres- ent knowledge, lends weight to the supposition that the area thus affected by movements was perhaps continuous completely across the Gulf.

In explanation of the distinctive form of atolls—the ring of coral with its inclosed lagoon—it is claimed by the oppo- nents of the subsidence theory that coral plantations building up from submarine banks will grow more rapidly on their outer margins, where the food supply is the greatest, and where, as compared with the inner parts of the mass, there is less obstructive sediment, and thus an exterior rim or eleva- tion would be formed. The differentiation of the inner and outer parts, it is assumed, would be further intensified by the removal in solution of the lime-carbonate from the less active interior portion—the region of coral decay and detrital accum- ulation—and the formation there of a shallow pan of water or lagoon. That the distinctive features of an atoll may be brought about somewhat in the manner here described can scarcely be doubted; indeed, the supplemental atolls of diminutive size that so frequently accompany the larger reefs, the serpula-reefs of the Bermudas for example, convincingly prove the possi- bility of ring structure without subsidence. But in instances of this kind the ring is merely a narrow projection, barely rising above the shallow central depression, and is due prob- ably more to the action of a beating surf than to any other cause. In the case of a true atoll with a large lagoon the con- ditions are very different, and it seeins impossible to explain the central depression, often 20, 30, and 40 fathoms, or even

THE CORAL-REEF PROBLEM. 63

more, in depth, on the assumption of internal solution, aided by external acceleration as dependent upon an increased food supply. It does not appear exactly clear why solution should progress more rapidly within the lagoon than over the deeper slopes of the coral buttress, where the protective power of the living animal is also wanting; nor is it at all likely that such solution as actually does take place within the lagoon more than compensates for the accretion of sedimentary material derived from the destruction of the surrounding shores, or for the organic accumulation that is continuously forming along the floor of the lagoon.

My examination of the Bermudas convinces me that, as far as those islands are concerned, the quantity of lime removed from the interior waters is far less than that which is added through sedimentation and organic development. ‘he bot- tom is everywhere covered with fine debris, and the even floor indicates that this debris is of considerable thickness. One has but to gaze upon the undercut and crumbling ledges of Harrington Sound and the cliffs facing the lagoon to be con- vinced that accumulation, and not solution, is the prevailing condition in these waters. Yet we have here a depth of water of from 50 to 80 feet. I am, indeed, far from convinced that the organic accumulation which is here taking place by actual growth does not far surpass the material removed through solu- tion. ‘The tests, both perfect and fragmentary, of Foraminifera are abundant everywhere, but in addition to material derived from this source, there exist large areas which are seemingly well covered with the shells of molluscous animals (Chama, Area, Avicula, etc.) and sea-urchins (Toxopneustes variegatus). The latter, with Arca Nox, are especially abundant. The coral growth of Castle Harbor, and not less the insular patches of millepore, etc., in the big lagoon, speak with suffi- cient emphasis on this point. There can be no doubt, too, that some of the basins and channels have been recently shallowing through silting, but of course this may have been brought about through a mere transference of material from

64 THE BERMUDA ISLANDS.

one point to another. The depth of water in the Flatts Inlet, which receives a strong tidal current from the outer lagoon and from Harrington Sound, is much less to-day than it was in the early part of the century, when the Inlet furnished a safe anchorage to vessels of large draught.

Mr. Bourne finds similar conditions to exist in the lagoons of the Diego Garcia reef, and he entirely rejects the theory that lagoons could have been primarily formed through solu- tion. He shows that nowhere has the lagoon deepened since the time when Capt. Moresby surveyed the region in 1837, but, on the contrary, evidences of shoaling to the extent of a full fathom on the south side are not wanting. It is also pointed out that the depth of water in the lagoons of the various islands which are associated with Diego Garcia is not propor- tional to the size of the lagoon, as we should naturally expect to find it in accordance with the theory of solution. This is also true of the Bermudian waters, although their relations somewhat differ from those of the Chagos Banks. Thus, the depth of water in the comparatively small Harrington Sound is measurably greater than that of the outer water, the big lagoon; it is also much greater than we find it in the superficially more extensive Castle Harbor.

Experiments made to determine the solvent power of sea- water show that the process of solution is a very'slow one. It appears indeed incredible, in the face of such energetic solu- tion as is presumed to exist in the upper waters of the ocean, that any extensive organic accumulation could ever take place over the floor of the sea, where the solvent power of the water is materially increased through pressure, and still less possible that any considerable foundation could be built up from it, or’ from the summit of only a moderately depressed mountain peak. ‘The fact that in so large a number of atolls the lagoons are either entirely wanting, or are reduced to mere shallow pans of water, also militates against the hypothesis of solution.

With regard to the formation of the primary ring through accelerated growth on the outer margin, as depending upon

A YI):

THE CORAL-REEF PROBLEM. 65

an increased food-supply, it may be reasonably doubted if this condition could obtain in the open ocean away from a land area, inasmuch as by far the greater quantity of the food-sup- ply.would be given to the polyps as a direct down-pouring from above, and independently, or nearly so, of any currental action. It is true that the outer polyps or colonies would be favored by having an extra supply on their exposed bor- ders, but ‘this would tend probably in the majority of cases only to lateral extension, or to lateral extension combined with upward growth—in other words, to a simple turbinated growth with a nearly flat top. It is true that in a few instances, as has been noted by Semper and Darwin, colonies of Porites, having a turbinated form, exhibit a raised border or lip, but it is equally true that in by far the greater number of cases the individual larger colonies assume either a clavate or a hemi- spherical form, the latter condition being also distinctive of the giant brain-corals. Mr. Bourne, from his researches on the Diego Garcia reef, also dismisses the notion that food-con- veying currents are especially instrumental in shaping the reefs, and he points out that frequently the most elevated side of an atoll is turned away from such currents, and, again, that a large number of coral islands are placed entirely to one side, or out of the path, of the prevailing ocean current.

But even granting that through some method of accelerated growth on the exterior an elevated bounding ring should be formed, the difficulty in accounting for the existence of the deep lagoon would in no wise be lessened; for, in the first place, no such ring would be formed below the line of coral growth, and we should consequently be compelled to assume as antecedent to its formation the complete upward growth or elevation of the submerged bank to the true coral zone, or to a greatest possible depth beneath the surface of 100 or 120 feet. Manifestly, under such conditions there could be no deep depression corresponding to lagoons of 200 or 300 feet depth, unless these were subsequently formed by means other than solution. Furthermore, it appears that the true energy

66 THE BERMUDA ISLANDS.

of coral growth is concentrated in the first zone of some fifty or sixty feet, which would practically mark the depth at which a bounding rim of accelerated growth would be formed, and also fix the depth of tlre lagoons.* But as has already been seen, the depth of nearly all extensive lagoons is very much greater, in some cases six times as great, or more.

The difficulty in the premises disappears almost entirely if we accept Mr. Darwin’s hypothesis of subsidence, for here the accelerated outer growth is assumed to depend no less upon interior retardation (as the result of the accumulation of in- jurious sediment), as upon an actual increase in the quantity of the food-supply. The depth and size of the lagoon will then depend upon the extent of land that has undergone sub- sidence, and upon the measure of its submergence. Where the descent is very gradual the upward development of the coral structures may by overgrowth completely close out the lagoon ; where, on the other hand, the descent is unusually rapid, more rapid than the compensating upward growth of the corals, a “drowned ” atoll may be the result. The great Chagus Bank, which is situated some 700 miles to the south of the Maldives and has a length of about 90 miles with a greatest width of 70 miles, has generally been assumed to be only a completely submerged or drowned atoll. If raised to the surface it would be in the form of a true atoll, with a depth of water in the lagoon of 40-50 fathoms. At the present time the bounding reef is covered with water of from 4 to 10 fathoms depth. The Bermuda Islands have also been instanced as an example of a partially drowned atoll, but, as has been shown in the preced-

*It is surprising that this consideration in the assumed formation of deep lagoons through accelerated marginal growth should be so generally overlooked. Prof. Hick- son, in his address before the British Association (1888) on ‘‘ Theories of Coral Reefs and Atolls,” furnishes an instance of such oversight. He says: “It seems very probable then that when a large submarine’ bank, by accumulation of sediment or by elevation, comes within the limit of coral growth, the growth commences and is almost confined to the edges of the bank, and that in course of time the edges of the bank reach the surface, whilst the centre of the bank has made little or no progress. This seems to be a very reasonable explanation of the deep lagoons of large atolls, and one to which at present I can see no valid objection.”

THE CORAL-REEF PROBLEM. 67

ing chapter, there is nothing in the present land-mass to indi- cate that it bears any direct relation to an atoll ring.

An objection that has been frequently urged against the sub- sidence theory, and one that has been more particularly in- sisted upon by Guppy as the result of extended observations made in the Solomon Islands, is that where fringing reefs are exposed they usually exhibit only a moderate thickness of true coral-rock, the basement or sub-structure being mainly of a pelagic character—that is, built up of the remains of pelagic animals (Foraminifera, etc). Hence, it is argued that in the so-called subsidence reefs—atolls and barrier-reefs,—the actual] thickness of coral is very limited, or barely more than that which would fall within the regular zone of coral growth. The few observations that have been made on this point, can- not be considered to throw much light upon the question, the more especially as the evidence obtained is far from corrobora- tive. Furthermore, it is just in such elevated reefs that in ac- cordance with the Darwinian theory we should frequently look for a thin deposit of coral-rock, for if there has been eleva- tion instead of subsidence the thickness must necessarily be slight; when, however, subsidence had preceded elevation the result would be the opposite. No weight should be attached to the oft-repeated assertion that in the older geological forma- tions there are no really massive reef-structures. This assér- tion is entirely opposed to the facts, to cite but a single instance presented by the Dolomites of the Tyrol, the reef-structure of which has been so ably worked out by Mojsisovies and others. Furthermore, it is practically impossible in the case of a large number of the altered limestones to state whether they are of coral origin or not.

One objection against the subsidence theory has still to be considered. It is the association of fringing reefs with atolls. This commingling of two distinct types of structure, implying movements in opposite directions, has been much commented upon, and placed under strong emphasis by the adherents of the new views regarding the formation of coral islands. But the occurrence appears to be entirely without significance.

68 THE BERMUDA ISLANDS.

An alternate movement of elevation and subsidence is no more strange over an oceanic area than it is on the continental borders. Yet we have here almost everywhere evidences of a differential movement, and no geologist has for a moment ex- pressed surprise at the manifestation. What then is the anomaly of the occurrence of such movements in a coralline sea ? How is the conception of subsidence antagonized by the facts of elevation? If we conceive of an atoll, with a deep lagoon, once having been formed through subsidence, what is to pre- vent a succeeding elevation from lifting parts of this atoll, or for that matter, the entire atoll-ring, above the water? We could still have the lagoon of subsidence retained, and yet asa last record of movement we would have merely the evidence of elevation. Because a certain structure is formed through subsidence it does not follow that this subsidence should not be followed by elevation. This is but the order of things we find everywhere expressed in the history of continental masses. Indeed it would be but natural to look for local oscillations in regions of extensive movement. Mr. Bourne lays great stress upon the evidences of elevation (of a few feet) which are pre- sented by Diego Garcia, and claims them to be conclusive against “the idea of any subsidence being in progress, as Mr. Darwin fancied to be the case in the Keeling atoll”*. I con- fess that I can find nothing in this evidence which would pre- clude an assumption of subsidence sufficiently recent to have produced the characteristic atoll form. We have in the elevated beach-rock of the Bermudas unequivocal evidences of elevation, but equally conclusive are the evidences of the subsidence which followed this elevation. In other words we have here the conditions of Diego Garcia simply reversed. Again, in re- gions where, as in that represented by the great Chagos Bank, it might be assumed that “ drowned ” atolls have been formed as the result of too rapid subsidence, a change of movement would be all but certain to develop reefs of elevation in combi- nation with those which are assumed to bear in their structure

*Loc. cit., p. 446.

THE CORAL-REEF PROBLEM. 69

the evidences of subsidence. In other words, there would be an interassociation in the same archipelago of both fringing reefs and atolls, for it can scarcely be conceived that all the project- ing land-masses of the archipelago could, at the time when movements of one kind or another set in, have been equally elevated above, or depressed beneath, the surface of the water. Hence, unequal developments must have taken place.

Such are the principal circumstances connected with the history of coral islands. If the theory of subsidence cannot, perhaps, be considered to be absolutely demonstrated, it ac- cords best with the facts, and, indeed, may be said to be in substantial harmony with them. Iurthermore, it helps to ex- plain the significant fact, first pointed out by Dana, that a very large, if not the greater, number of coral structures are ranged along the line of greatest depression in the sea.

The question hete naturally suggests itself: Is there any evidence supporting the theory of assumed subsidence of the oceanic basins beyond what is furnished hy the coral islands? It must be admitted that our positive knowledge on this point is very limited—indeed, almost nothing. But various considerations lead to the belief that the present site of the oceanic basins is a very ancient one, and possibly one that has not materially changed, except in so far as intensification is concerned, since it was first marked out as the most prominent feature of the earth’s crust. While manifestly we can have no proof of this condition, it seems but reasonable to assume that if this vast depression was formed through an early flexure of the crust, and as the result of weakness in certain parts of that crust, it has retained its position of depression from the first. With a contracting or moving crust, moreover, particularly under the special conditions of loading (sedimentation) and continental unloading (denudation), it is likely that a depres- sion of this kind would tend to sink or to subside, and force a relief from strain in the uplift of the continents. This is the view now held by probably the greater number of physicists

70 THE BERMUDA ISLANDS.

and geologists. But it does not carry with it the assumption of a necessary permanence in the positions of continents and oceans; it does not imply that the oceanic basins were originally of the extent that they are to-day, as we are led to believe by many geologists. It is far more probable that the existing dimensions have been brought about through pro- gressive or cumulative subsidence, which has gradually swept away land-masses that at one time occupied some of the pres- ent area of the sea. The long lines of ridges which have been revealed to us by deep-sea soundings, and the placing on these of many of the oceanic islands (volcanic peaks), together with the evidence which the past and present distribution of animal life carries with it, all support this conclusion. It seems, in- deed, impossible to account for the existence of oceanic (vol- canic) islands, or for the negative islands which rise as promi- nences from the oceanic floor to within a comparatively short distance of the surface, except on the assumption of subsidence. What is the significance of buttresses like St. Helena, Ascen- sion, the Caroline Islands, or the giant peaks of the Sandwich Tslands rising from depths of two or three miles, or more? Can it be assumed that they have been steadily built up vol- canically from the ocean floor, four or five miles in height? This is, perhaps, not impossible, but it hardly appears prok- able. Vulcanism in one form or another doubtless manifests itself over the floor of the ocean, but all indications point to a comparatively limited action in the greater depths. Were submarine eruptions at all numerous, or of that intensity which might be assumed to be necessary for the construction of a giant mountain-peak, we should be probably made aware of their existence in a manner not less emphatic than in the case of subaerial eruptions. It might be assumed that the long intervals at which eruptions take place would prevent special notice of such phenomena, and that, consequently, their effects, even if most momentous, would be placed prac- tically beyond observation. But this is not likely to be the case. When we consider the large number of peaks that in

THE CORAL-REEF PROBLEM. 71

one form or another come to, or beyond, the surface, and real- ize how few of them are in a condition of activity, it is diffi- cult to believe that many of these peaks are to-day in a course of volcanic construction, or that other submarine peaks, scat- tered between these, are undergoing a similar process of for- ‘mation. It seems far more natural to assume that these peaks or islands have been for a long time fully formed, and that they were formed at a time when their relations to the sur- rounding sea were more nearly those which govern the posi- tions of by far the greater number of the active volcanoes of to-day. In other words, they were probably continental or sub-continental, and their present positions are the indices of continental subsidence; the vast mass of overflowing water may have extinguished the fires that at one time supplied the material for eruption.

The recent discovery of a large number of submarine peaks, whose existence had not previously been even surmised, rising to within a comparatively short distance of the surface, seems to support the general conclusion of subsidence. The sound- ings of telegraph ships indicate that between the latitude of Lisbon and the island of Teneriffe there are not less than seven peaks over which the depth of water varies from not more than 12 to 500 fathoms. From the entire oceanic basin it is claimed that there are already known about 300 such “submarine cones, rising from great depths up to within depths of from 500 to 10 fathoms from the surface’*.

Probably the greatest difficulty that lies in the way of the acceptance of the subsidence theory of coral structures is the fact that there are not more islands which are in a condition of semi-formation—. e., peaks, partially submerged and sur- rounded by an encircling barrier reef. This is not an in- superable objection, and might be treated by some geologists in the nature of negative evidence. But the fact is of signifi- cance, and must be taken into account for whatever it may be

*Murray: Aafure, Feb. 28, 1889, p. 425,

72 THE BERMUDA ISLANDS.

worth, in all theories bearing upon the formation of coral islands.

Since the preceding notes were sent to press Alexander Agassiz has published his observations on the “ Coral Reefs of the Hawaiian Islands.”* This paper, apart from giving de- tailed descriptions of the reefs of the Sandwich Islands, presents, on the whole, perhaps the clearest statement of views bearing upon the structure of coral islands that has yet been published, but it can scarcely be said that it contributes materially toward the solution of the general problem. Mr. Agassiz asserts himself to be a pronounced opponent of the theory of subsidence, as, indeed, he has always been since he first undertook the very careful survey of the Florida reefs. I think it will be generally admitted, however, that the evi- dence which is now brought forward is, as far as the substitute theory is concerned, almost wholly negative, while much of it favors the theory of subsidence. Mr. Agassiz assumes certain definite premises or propositions, which are dogmatically stated, but it is difficult to find the exact evidence upon which these premises are based. The special points of evidence which, in the opinion of this authority, render the subsidence theory unnecessary and untenable are practically the same as those which have already been discussed, and consequently they call for but little detailed consideration.

Mr. Agassiz considers it “remarkable that Darwin, who is so strongly opposed to all cataclysmic explanations, should in the case of the coral reefs cling to a theory which is based upon the disappearance-of a Pacific continent, and be appar- ently so unwilling to recognize the agency of more natural and far simpler causes;” and he further expresses himself: “as long as we can in so many districts explain the formation of atolls and of barrier reefs by other causes, fully sufficient to account for the numerous exceptions to the theory of Darwin, which have been observed by so many investigators since the

*Bulletin Mus. Comp! Zoology, XVII, April, 1889.

THE CORAL-REEF PROBLEM. 73

days of Darwin and Dana, it seems unnecessary to account for their presence by a gigantic subsidence, of which although we may not deny it, we can vet have but little positive proof” (p. 131). These reflections are well so far as they go, but have the “natural and far simpler causes” underlying the forma- tion of coral reefs, which are to take precedence over the Dar- winian hypothesis, been satisfactorily demonstrated? I believe not, and I further believe with Dana and Von Lendenfeld that no facts that have yet been brought forward stand in direct op- prsition to the theory of subsidence.* Mr. Agassiz assures us that the “ Mosquito Bank, the Yucatan Bank, and the smaller banks between Honduras and Jamaica, are all proof that limestone banks are forming at any depth in the sea, or upon pre-existing telluric folds or peaks, constituting banks upon which, when they have reached a certain depth, corals will grow © (p. 133), and a similar condition is considered to under- lie the formation of the Florida reefs. It has, however, not been shown that these banks have been actually built up in the manner that has been described, or that any other banks have been similarly reared from really great depths. The assertion that the Florida reefs have not been assisted in their upward growth by elevation (p. 142) is, as far as I can see, not supported by fact, for we have in the regular horizontal lime- stone beds of the southern part of the peninsula the most con- clusive evidence of elevation even as late as the Pliocene and Post-Pliocene periods. and there is every reason to believe, even if the condition cannot be proved, that this upward movement did not stop short of the coral-forming tract. Nor does this movement of elevation preclude the possibility of subsidences having taken place coincidentally in the same re-_ gion. It appears to me by no means certain that the deep channel now separating the apex of the peninsula of Florida from Cuba, and known as the Straits of Florida, was really cut by the Gulf Stream, as is maintained by Mr. Agassiz. It seems to me far more probable that it, as well as some of the

“* Natur wissenschaftliche KRundschau, Oct. 13, 18SS.

74 THE BERMUDA ISLANDS.

other deep channels separating the West Indian Islands, was formed through subsidence—the result of localized breakages in the crust. This view has already been expressed by Suess,’ who draws a close parallel between the physiographic con- struction of the basin of the Gulf of Mexico and that of the Mediterranean. 7

Mr. Agassiz thinks it “somewhat surprising that, in the dis- cussion which has lately been carried on in the English re- views by the Duke of Argyll, Huxley, Judd, and others, regarding the new theory of coral reefs, no one should have dwelt upon the fact, that, with the exception of Dana, Jukes, and others who published their results on coral reefs soon after Darwin’s theory took the scientific world by storm, not a single recent original investigator of coral reefs has been able to accept this explanation as applicable to the special district which he himself examined ” (p. 183). This condition may be surprising, but it is not less surprising that the different in- vestigators who have rejected the Darwinian hypothesis should have thus far failed to agree among themselves as to their own special theories. Thus, the “solution theory ” of the formation of the atoll-lagoon, which has been so much emphasized by Mr. Murray, and the possibilities of which we have already discussed, is practicably rejected by Bourne, Guppy, and Wharton’, and even Agassiz expresses himself not fully satis- fied with its efficiency. And as far as I know no satisfactory explanation of the formation of the deep lagoons has been given by any of these investigators. Captain Warton has re- cently described* a number of submerged reef-structures in the China Sea which have a deep flat centre, surrounded by. _ an elevated growing rim; it is assumed that were this rim to grow up to the surface we would have the characteristic feat- ures of an atoll, with its deep central lagoon, presented. But

1‘Antlhits der Lerde, I. 2NMature, Feb. 28, 1888. 3Loc. cit., p. 893.

THE CORAL-REEF PROBLEM. 75

there is no evidence to show that these submerged atoll-like banks are not really banks of subsidence, rather than of up- ward growth, and in their general features they do not differ from the Chagos Bank which Mr. Darwin considered to repre- sent a half-drowned atoll. Until a satisfactory explanation is furnished of the origin of these central lagoons, so long must any theory bearing upon the formation of coral structures be considered merely tentative. In the case of the Bermuda Islands, which limit the field of my own investigations in this direction, I am confident that, whatever may have been the original construction of the region, the present lagoon features have been brought about through subsidence; and this con- clusion was reached before me by Prof. Rice, who seems to have been amply satisfied with the subsidence theory!

On one point in connection with his recent survey Mr. Agassiz furnishes important testimony, and that is as to the actual thickness of the coral-made rock, or, at least, the depth beneath the surface at which this rock occurs. This has been determined by the artesian borings made in the vicinity of Honolulu, and elsewhere. At various points the bore pierced coral-rock at depths of 100-500 feet beneath the sea-level. In the well of Mr. James Campbell, near the Pearl River Lagoon (?), 28 feet of white coral was struck at a depth of nearly 1000 feet below high-water mark (p. 153), and again at “ Waimea, Oahu, 900 feet was drilled through hard ringing coral rock ” (p. 152). In these facts, however, Mr. Agassiz sees no evidence of sub- sidence. He prefers to account for the great thickness of the coral rock “ by the extension seaward of a growing reef, active only within narrow limits near the surface, which is constantly pushing its way seaward upon the talus formed below the liv- ing edge. This talus may be of any thickness, and the older the reef, the greater its height would be, as nothing indicates that in the Hawaiian district there has been any subsidence to account for such a thickness of coral rock in its fringing reef” (p. 154). But where are the evidences which support this ex- planation? I must confess that I fail to see any. The assump-

76 THE BERMUDA ISLANDS.

tion of a seawardly-extending talus of coral is, it appears to me, purely gratuitous. Indeed, with the very gentle slope that these islands have beneath the sea it is extremely doubtful if any extensive talus could accumulate as a result of either downflow or downwash. Prof. Dana has well supplied the argument on this point, and its seems to me that it is unan- swerable. With a gradient of perhaps eight degrees, and not impossibly much less, it is almost inconceivable that there should be much lateral spread of detached coral boulders. Neither wave-action nor the action of the oceanic currents, except possibly under conditions of earthquake disturbance, would be likely to effect the required displacement.

Again, it might be asked, what kind of direct evidence must we look for to establish the point that there has been no great progressive subsidence in the Hawaiian Islands? The needed evidence is just of that kind which it pleases the Earth to keep to herself, and after which the geologist has in most instances sought in vain. The fact that cinder-cones are found “ with their base close to the present sea-level” proves, it appears to me, nothing in this connection, and I fail to see the argument which draws from their existence a proof of non-subsidence. But Agassiz himself admits that there is ‘some evidence of subsidence [about 50 feet] on the southern shore of Hawaii” (p. 154).

On the whole, it seems to me, that the facts as they are pre- sented are, if they indicate anything at all, directly in favor of subsidence, and of subsidence on an extensive scale. They are in my mind far more conclusive than the somewhat simi- lar facts which have been generally accepted by geologists to prove depression or subsidence in delta-deposits, such as those of the Mississippi or Ganges. Dr. W. O. Crosby, in his paper on “The Elevated Coral Reefs of Cuba,”* shows that the coral limestone of Cuba is in places at least a thousand feet in thickness, and he naturally infers that there must have been

*Proc. Boston Soc. Nat. History, XXII, 1882-83, p. 124.

THE CORAL-REEF PROBLEM. 77

subsidence to nearly this amount. Mr. Agassiz, commenting on this important observation, says (p. 150, note) that it does “not throw any additional light on Darwin’s theory of sub- sidence; it is of the same character as all the statements which prove the subsidence by the existence of coral reefs, and while there may have been coral reefs formed during sub- sidence, it does not prove that their growth is due to subsidence any more than the presence of elevated reefs proves them to be due to elevation.” This criticism is in a measure valid, but it must be remembered that one of the “strong” points urged by Guppy and others against the subsidence theory was the (supposed) non-existence of massive deposits of coral-lime- stone, or such as indicated formation through protracted sub- sidence. But here we surely have such a limestone (provided the observation is correctly made), and its presence removes what might have been a valid argument against the Darwin- ian hypothesis. And further, there is reason to believe that the thousands of feet of reef-structure which have been de- scribed by Sawkins in Jamaica are largely, if not mainly, of coral growth, and represent a formation produced during a long period of subsidence.

In the foregoing discussion of the structure of coral reefs, as also in the chapter treating of the physical history of the Ber- mudas, I have used the term “subsidence” (and necessarily its opposite—elevation) in a relative sense, indicating a depression or submergence of the land beneath the sea. But whether this submergence was due to a positive movement on the part of the land, or to a change of level (rise) in ‘the water, cannot readily be determined, as the phenomena attending either form of movement would be practically identical. The broad problem of oceanic transgression and continental stability, which has been so forcibly outlined by Suess, cannot be properly treated in this place.

V.

THE RELATIONSHIP OF THE BERMUDIAN FAUNA.

Mr. Wallace, in “Island Life,” has ably discussed the more general features of the Bermudian fauna, and analyzed the conditions which gave to the fauna its distinctive characters. The new material which we were fortunate to obtain enables us to enter further into the discussion, and to supplement and expand the conclusions which had been reached from the study of only a limited number of animal groups.

In its broader aspects the Bermudian fauna is strictly non- continental; it lacks those elements which we associate with the animal life of any extended land area, while negatively, in the paucity of animal forms in general, it presents a character- istic of insular faunas. The deficiencies in both the higher and the lower groups of animals are well marked, and the number of special types represented is not very great. The vast body of water which separates these islands from the mainland has, as might have been anticipated, largely prevented the crossing of American animals, and this is true of all the groups except volants. Barring the two species of whale—right-whale and sperm-whale—which visit the waters of the archipelago, the only “wild” mammalian forms of the region are bats, rats, and a possible shrew (Sorex). The animal supposed to be a shrew is referred to by Matthew Jones (Mammals of Bermuda, Bull. U. S. National Museum, 1884), but unfortunately no positive identification has been made. Four species of rat— the brown or Norway rat, the black rat, the tree or roof rat (Mus tectorum), and the common mouse (Mus musculus)—are re-

RELATIONSHIP OF THE FAUNA. 79

corded; the black rat, as elsewhere, is rapidly disappearing, and is now on the verge of extinction. There is little reason to doubt that some, and possibly all, of these forms were trans- ported to the islands in the holds of vessels, just as they have been carried from Europe to America, but no absolute date can be fixed for the first rat visitation. If the accounts of Jourdan are to be credited, no rats were known prior to about 1610, although only a few years later (1618) the islands appear to have been largely overrun by the tree-rat, and to such an ex- tent that, as Captain John Smith, in his History of Virginia, says, ‘there was no island but it was pestered with them; and some fishes have been taken with rats in their bellies, which they caught in swimming from ile to ile; their nests had almost in every tree, and in most places their burrowes in the ground like conies; they spared not the fruits of the plants, or trees, nor the very plants themselves, but ate them up” (Jones, p. 158). This great abundance, as Matthew Jones well remarks, points toa much earlier colonization than the purely historical data indicate, allowing even for the most rapid development that these animals are capable of. It would, indeed, be some- what surprising if these animals had not made an earlier ap- pearance, for it can be readily conceived that at least some individuals, more particularly of the tree-rat, would have found their way over, if not through the agency of vessels, on the drift timber which must at times have reached the islands. The narrative of Americus Vespucius, as bearing upon the islands of Fernando de Noronha, is interesting in this connec- tion, since it shows that these islands, which lie directly in the line of the westward-sweeping equatorial currents, were in- habited by a form of big rat as early as 1503, the year of Vespucius’s fourth voyage. How and whence this animal came to the islands it is impossible to say, but not unlikely, as has been suggested by Mr. Wallace and Prof. Branner,* it, together with a species of amphisbeenian, may have been cur- rentally distributed from Western Africa, a supposition that

*Branner, Fauna of the Islands of Fernando de Noronha—Amet. Naturalist,

Oct., 1888, p. 871.

80 THE BERMUDA ISLANDS.

seems not unlikely in view of certain anomalies of distribution which are presented by the Bermudian fauna.

Up to the present time there have been recorded from the Bermudas four species of bats, two of which, the silver-haired bat (Vesperugo noctivagans) and the hoary bat (Atalapha cinerea), are common North American forms, while the remaining two (Trachyops cirrhosus—a vampire—and Molossus rufus, var. obscurus) are more strictly tropical, ranging over much of South America and the West Indian Islands. Specimens of the last two, coming from the Bermudas, are in the collections of the British Museum, and appear in Mr. Dobson’s Catalogue (1878). These animals must, however, be of extremely rare oecurrence in the islands, since they were unknown to both Mr. Jones and Mr. J. L. Hurdis, the latter a fourteen years resident. The silver-haired bat is about equally rare, as but a single specimen seeins to have been noticed in the island group, and that one nearly forty years ago.* Even the commoner ‘form (Molossus obscurus) is very uncommon, and appears only in the autunin months, when the westerly storms bring over numbers of American birds. So rare, indeed, are these animals generally that they are seemingly unknown to the majority of the inhabitants, and even among the older resi- dents I found but little knowledge of cheiropterology. It is singular, in view of the scarcity of these animals, that Capt. Nelson should have considered the “red earth” of the Ber- mudas, and also of the Baliamas, to have been formed largely as an accumulation of the rejectamenta of bats, which in- habited “once-existing caverns” (Journ. Geol. Soc. London, IX, p. 209). We observed no bats in any of the caves or caverns which we visited, nor.did “ancient” guardians of these caverns know anything about such animals. The very rare occurrence of bats in the islands, and the circumstance that they are most conspicuous during the periods of heavy storms, prove almost conclusively that these animals are merely in- blown stragglers.

*Jones, Mammals of Bermuda, of. cit., p. 145.

COCOANUT PALMS

RELATIONSHIP OF THE FAUNA. 81

The bird fauna of the Bermudas, including both land and water forms, comprises, as far as is known, some 187 or 188 species, which, with two or three exceptions, are members of the North American fauna. These exceptions are the sky- lark (Alauda orvensis), common European snipe (Gallinago media), and gold-finch (Carduelis elegans). The first, of which but a single specimen has been obtained, has generally been considered to be an escaped cage-bird, but Savile Reid, in his review of the birds of Bermuda (Bull. U. S. National Museum, No. 25, 1884, p. 178), believes it to have been more likely an inblown straggler. Seemingly only two specimens of the European snipe have been recorded, both of them from Pem- broke Marsh, where they were shot in December 1847, by Colonel Wedderburn. The single specimen of gold-finch was observed by Savile Reid near Harrington Sound, in April, 1875; it was very wild, but is still supposed to have been an escaped prisoner. Two other European birds, the wheat-ear (Saxicola enanthe) and land-rail (Crex pratensis), have also been noted in the Bermudas, but both of these find their way to Greenland and the mainland of America, so that their occur- rence is less remarkable than that of the other forms.

Of the entire Bermudian avifauna somewhat less than one- half the species are land-birds, and of these a fair proportion have been observed only on one or two occasions. There appear to be but eleven permanent residents, nine land-birds, and two water-birds, to wit: cat-bird (Galeoscoptes Carolinensis), blue-bird (Sialia sialis), white-eyed vireo (Vireo Noveboracensis), English sparrow (Passer domesticus), cardinal-bird (Cardinalis cardinalis), crow (Corvus Americanus), Virginia quail (Colinus Virginianus), ground dove (Columbigallina passerina), great blue heron (Ardea herodias), Florida gallinule (Gallinwa galeata), and tropic-bird (Phaéton flavirostris). Two or three species of shearwater (Puffinus Anglorum, P. obscurus, ? P. opisthomelas) have at intervals been found breeding in the Bermudas, but seemingly they have now deserted these islands for other

82 THE BERMUDA ISLANDS,

quarters.* Mr. Savile Reid informs us that the presence of the Virginia quail or “ bob-white” marks a recent introduction, the bird having entirely disappeared from the islands with the year 1840; an importation from the United States was made in 1858 or 1859, and is the orgin of the existing stock of birds.

Mr. Witmer Stone, one of my assistants, has furnished me with the following notes on non-resident birds observed by him during our visits to the islands in the month of July, a season of the year when the bird fauna is probably at its minimum:

Wilson’s petrel (Oceanites oceanicus). A single individual seen in the wake of the steamer a sliort distance out from the islands.

Least sandpiper (Tringa minutilla). Several individuals seen near Spittal Pond, July 15.

Piping plover (digialitis meloda). A single individual, which followed in the wake of the departing steamer for the better part of a day.

Green heron (Ardea virescens). A single individual observed in the'mangroves of Walsingham.

We heard or saw all the resident birds of the islands with the exception of the great blue heron (Ardea herodias). The first tropic bird was seen before the land was yet sighted, and from this time until our departure we seldom lost sight of these beautiful creatures. At the time of our visit the breeding season was nearly over, and the nearly fledged young were to be seen sitting on the ledges overhanging the waters. The single egg is deposited in holes in the rock, which are apparently excavated by the parent. We found the birds breeding both on Har- rington Sound and on the south shore. The little English sparrow was also found breeding among the shelving rocks of Harrington Sound. We observed but three crows during our sojourn, and it would appear that this bird, which was at various times abundant, even as early as the beginning of the

*Mr. Wallace mentions the coot as 4 permanent resident, but probably the bird intended is the gallinule.

RELATIONSHIP OF THE FAUNA. 83

seventeenth century, and as late as the last decade, is again be- coming rare.

The most regular and abundant, among land-birds, of the “regular” visitants are the small-billed water-thrush (Seiwrus Noveboracensis), snow bunting (Plectrophanes nivalis), bobolink (Dolichonyx oryzivorus), night hawk (Chordeiles Virginianus), and belted kingfisher (Ceryle alcyon), some of which arrive and go with almost strict punctuality to season. The pigeon-hawk (Hypotriorchis columbarius) and osprey (Pandion haliaétus), as also one or two species of owl, are somewhat less regular, but not exactly uncommon. If we except the Seiurus, all these birds are either partial migrants or hard fliers, and it is not difficult to account for their presence in the islands. Some of them, doubtless, reach the Berniudas in the direct line of their migration, and are not wind-borne. The regularity of the ar- rivals proves this almost beyond question, as it likewise does in the case of the numerous water-fowl—sandpipers, plovers, snipe, ete,—which so largely abound during the seasons of migration. The condition is otherwise with the birds that have been met with only at long intervals or on single occasions. There can be no question that these are wind-swept, and have been involuntarily carried seaward by sudden storms. Some of the more delicate birds, such as the warblers, tits, and hum- ming-bird, have thus managed to reach the islands, while, doubtless, many more perished in the interval separating them from the mainland. It is interesting to note that even such a large bird as the American swan should have crossed this stretch of the ocean, but it is diffcult to conceive that the pres- ence of this bird is due to simple wind-drift. May it not bea case of misdirected flight, following the lead of some other birds? Possibly the exceptional occurrence of the flamingo (Phenicopterus ruber) may be similarly accounted for.

Excluding the marine turtles which visit the waters there is but a single reptile in the islands. It is a skink, Eumeces longirostris, a form closely related to the common skink of the

84 THE BERMUDA ISLANDS.

Eastern and Southern United States, Humeces fasciatus. The animal is said to be very common, but we saw and obtained but a single specimen. Until within the last few years the batrachians were wholly wanting from the Bermudas, or at least supposed to be so. Latterly, specimens of the big Bufo marinus were introduced; and seemingly the new toad does well. We saw several of these animals in the brackish waters near the Devonshire marshes. Not unlikely a species of cecilian also belongs to the Bermudian fauna, and may indeed be indigenous. We obtained from under a stone a number of eggs beaded to one another in the form of a string, which I was unable to place. Prof. Ryder, of the Univer- sity of Pennslyvania, has kindly examined these for me, and he believes that they are the eggs of ceecilians. They certainly bear a very close resemblance to the figures and descriptions of the ova of the Cecilia, and most so, perhaps, to those of the genus Cecilia itself. It would be interesting to determine to what animal the eggs really belonged. They measured about 5 mm. in diameter.

The preceding enumeration of species brings prominently to light three important points in zoogeography: 1. The im- poverished character of the vertebrate fauna; 2, the distine- tively American, and more particularly, North American, aspect of this fauna; and 3, the general absence of forms peculiar to the islands. These conditions would seem to im- ply a permanent (past) isolation of the islands from the near- est mainland, and a comparatively brief existence. But this need not necessarily have been the case. Even if we admit a former connection with, or near approach to, the American continent, for which, however, there appears to be but little, if any, satisfactory evidence, we could scarcely hope, under the conditions which have marked the history of the Bermudas, to have retained many elements of a continental vertebrate fauna. The restricted area and absence of freshwater, in con- junction with the depredations of birds of prey, would have soon exterminated, or all but exterminated, what there may

RELATIONSHIP OF THE FAUNA. 85

have been of mammals, reptiles, and amphibians, leaving but a few groups—bats, rodents—as possible survivals. Nor could we reasonably expect to find the remains of such animals preserved either in the coral rock or inthe drift-rock of the islands. With regard to the question of the recent origination of the islands the evidence from the vertebrate fauna proves little. The great distance of the islands from the mainland in itself explains the poverty of the fauna, whether this be old or new, while the absence of distinctive or special types among birds is, as Mr. Wallace well holds, due to the too frequent crossing of migrants or involuntary wanderers, which keeps the various breeds true, and prevents specific modification. The absence of peculiar species is, therefore, not a result of newness; on the contrary, certain considerations seem to indi- cate that the island group is of greater antiquity than has been generally assumed, and not impossibly some of the lower forms of life now inhabiting it are descendants of an ancient fauna which was well developed before the present physical conditions were established.

An analysis of the Bermudian invertebrate fauna shows some very interesting and remarkable features, which prove the complexity of zoogeographical inquiry. Before our visit but little systematic work—for most of which we are indebted to Matthew Jones—was done in this department of zoology, and, doubtless, much still remains to he done. But the general features of this fauna are now sufficiently determined to per- mit of satisfactory conclusions being drawn from them.

The marine Mollusca of the archipelago, which up to the time of our visit were listed at about 80 species, comprise, as far as is now known, some 170 species. These, with probably less than a dozen exceptions, are all members of the West Indian or Floridian faunas. Lying in the path of the Gulf Stream drift, which strands upon the island-shores vast quanti- ties of the Gulf-weed (Sargassum bacciferum), there seems little reason to doubt that by far the greater number of these forms

86 THE BERMUDA ISLANDS.

were given to the region from the south. The species peculiar to the Bermudas are, as far as is now known, about eleven in number, none of which had been described previous to our exploration. ‘They are:

Octopus chromatus,

Aplysia xquorea,

Chromodoris zebra,

Onchidium (Onchidiella) trans-Atlanticum,

Emarginula dentigera,

Emarginula pilewn,

Cxcum termes,

Macoma eborea,

Mysia pellucida,

Cytherea Penistoni,

Chama Bermudensis.

In addition to the above there are several shells (Phos, Columbella, Pleurotoma) which I have been unable to place, and which may prove distinctive of this fauna. On the other hand, it is not impossible that some of the forms above named may be found elsewhere, and thus lessen the amount of in- dividuality which the Bermudian fauna now presents. Thus, the Murex nuceus, of Mérch, which was supposed to be peculiar to the Bermudas, has recently been found at Marco, west coast of the peninsula of Florida; and a species of Cythara, (unnamed) which I obtained at Shelly Bay, I have since found among unidentified material, from Florida, contained in the collections of the Academy of Natural Sciences. But the facts as they stand are sufficiently suggestive, and in conjunc- tion with much more marked peculiarities presented by the terrestrial Mollusca, point strongly, though by no means con- clusively, to a faunal individuality that could have arisen only as the result of long existence, or of a faunal modification that was unusually rapid in its development. How rapid this modifi- cation may have been, or how old the islands may be, it is im- possible to say, and the terms can, therefore, only be used in a relative sense; but with either condition an antiquity is indi-

RELATIONSHIP OF THE FAUNA. 87

cated which extends probably far beyond the time that is generally associated with the making of “recent” coral islands.

The number of terrestrial mollusks credited to the Bermudas is usually given at 19 or 20, but the list which appears further on shows that this number must be increased to 30. An anal- ysis of this list indicates that of the thirty species sixteen, or somewhat over half, are known also from the West Indian islands, five (Helix vortex, H. microdonta, H. pulchella?, H. appressa, and Pupoides fallax) occur in the United States, three in Europe or the East Atlantic islands (Madeira, Azores— Helix ventricosa, Helix pulchella, Cecilianella acicula), while not less than eight, including all the species of the remarkable group Pecilozonites, appear to be confined to the Bermudas. These species are: Helix discrepans, Poccilozonites Bermudensis, P. cir- cumfirmata, P. Reiniana, Succinea Bermudensis, Alexia Bermuden- sis, Melampus Redfieldi, and Helicina convexa. To this number may perhaps also be added the somewhat doubtful Helix hypolepta. The large proportion of special forms, taken in con- junction with the development of a distinct group, is certainly remarkable in the case of an island group which has been generally considered to be recent in formation, but this spe- cialization is also well marked in some of the other animal groups. The fact argues for considerable antiquity, and it is interesting to note in this connection that the ancestral type of the peculiar molluscan genus Pecilozonites is represented in the common sub-fossil ‘P. (Helix) Nelsoni, the probable progeni- tor of the recent P. (Helix) Bermudensis.

The conditions governing the dispersal of the terrestrial Mollusca have been fully discussed by Mr. Darwin and Mr. Wallace, and there can be little or no doubt that their explana- tion of the oceanic transport of these animals is the true one. The floating material of the Gulf-drift has in this instance, doubtless, sufficed to bring most, if not all, of the non-peculiar species of the islands from the West Indies and the Southern United States, A few of the species, again, may have been

88 THE BERMUDA ISLANDS.

transported by vessels, or even through the agency of birds. The interesting question here naturally presents itself: Of what relation to the Bermudian fauna are the two or three identical species—Helix ventricosa, H. pulchella, and Cecilianella acicula—which occur in the East Atlantic islands (Azores, Madeira, Canaries) and Europe? Are they a part of the west- ern fauna which has gradually drifted eastward, and stocked the European continent from a home originally insular? The species (two, at least) have seemingly not yet been found in the western hemisphere outside of the Bermudas, and possibly they do not occur elsewhere. If this is the case it is hardly likely that they could have been carried (except through the agency of man) from the Bermudas to the Azores or the Canaries, since the first-named islands lie considerably to the eastward of the Gulf current, although still within the influence of the Gulf- drift. The fact that none of the species of the peculiar genus Peecilozonites are found in the Azores or the Canaries is a fur- ther argument against an assumed eastwardly transport. On the other hand, it is just possible that the Bermudas have received these species from the Azores and Canaries through the return Lusitanian and equatorial currents, and that the Azores fur- nished to Europe the continental representatives of the species. There would be nothing strange in this, and the northern posi- tion of the return currental flow might explain the absence of these forms from the West Indian Islands. That islands, which are favorably situated as far as winds and currents are con- cerned, should have.transmitted to continental areas portions of their faunas is what we should but expect. It is not only that the continents furnish the islands, but necessarily the islands must furnish the continents, but to what extent this reciprocal action takes place cannot well be determined. From various considerations Morelet has argued that some of the molluscan forms of meridional Europe must have originated in, or, at least, been derived from, the Azores. If the ocean currents which now pass off the Southeastern United States trended in the opposite direction there can be no question that

RELATIONSHIP OF THE FAUNA. 89

some of the peculiar Jand-snails of the Bermudas would be drifted to our shores, where, with a favorable climate and vege- table growth, they would soon multiply and spread, and to such an extent as to make it appear as though they originated on the continent.

It might be objected that these seeming anomalies of dis- tribution can be readily accounted for by assuming that there has been simple artificial transport by means of vessels. And, no doubt, full allowance must be made for this contingent dis- tribution. But, again, on this assumption the absence of the commonest species of land mollusks—those which have been most broadly distributed over the earth’s surface, and which would have found congenial conditions of environment in the Bermudas—becomes very striking, and equally so whether we consider the forms that may have been transported from the Old World or from the New.

The marine molluscan fauna of the Bermudas is, as has already been seen, overwhelmingly Antillean in character, and there can be no question that its own history is intimately bound up with the history of the fauna of the West Indies. The practically total absence of species of the Eastern United States which are not found in the Floridian waters is astonish- ing, and shows how insuperable is the barrier which the waters of the Atlantic, arid of the Gulf stream particularly, offer to a free migration or dispersion of the species. This, again, ap- pears the more remarkable in the light of certain anomalies of distribution which a critical examination of the species reveals, and which had already in many cases been noted as a charac- teristic of the West Indian fauna. Thus, the various species of Triton, Yriton chlorostoma, T: tuberosum, T. cynocephalus and 7. pileare, are all members of the fauna of the Pacific and Indian oceans; Ranella cruentata crops up in the variety L. rhodostoma, from Mauritius. Again, Epidromus concinnus, from the Philip- pines, is represented in our collection by a number of individ- uals which are absolutely undistinguishable, both in shell or- namentation and color-markings, from the Pacific specimens,

90 THE BERMUDA ISLANDS.

while they differ somewhat from the closely related Epidromus Swifti, from Antigua. A seemingly undescribed form of Col- umbella (Anachis) is, so far as I have been. able to determine, most nearly related to a species from New Caledonia, Anachis plicaria ; Natica Marochinensis is a member of the faunas of both Western Africa and the Pacific, and Natica lactea is apparently undistinguishable from WN. Flamingiana, from the Viti (Feejee) Islands, Philippines, etc. whence we have also the Arca imbricata. A number of forms common to the west coast of Africa and to the southern waters of Europe also occur, but these appear to be less numerous than the forms which occur in the Pacific’ and Indian oceans. Seemingly but few of the Bermudian species are found in the Azores (Purpura hemastoma, Neritina viridis, Avicula Atlantica, Pinna rudis), a somewhat surprising circumstance in view of the large representation of Pacific forms, and considering that the Azores lie directly in the path of the heated waters of the Gulf Stream. It is, indeed, difficult to account for these anomalies of distribution, and for still more marked ones, as we shall presently see, which are presented by the Crustacea.

Of molluscan forms which have been hitherto considered to be restricted to the west coast of America, I can state the positive occurrence of only two or three species—Chama exogyra, Tellina Gouldii, from the Californian coast. In the case of both of these forms I have very carefully satisfied my- self as to absolute identity. Arca solida, from the west coast, does not appear to differ measurably from Arca Adamsi, a West Indian form which has its representative in the Ber- mudian fauna. I feel satisfied that many more forms are common to the east aud west coasts of America than is generally assumed to be the case.

There appears to have been no systematic determination of the Bermudian Crustacea prior to our visit to the islands. The collections made by us are not extensive, but probably a full half of the species which they contain are now for the first time recorded from the archipelago. By far the greater

RELATIONSHIP OF THE FAUNA. 91

number of species—indeed, nearly all of them—are, as would be naturally expected, forms which belong to tropical or sub- tropical America (Florida, West Indies, Brazil). None of the species, as far as they have been determined—the Isopoda and Amphipoda still await examination—are peculiar to the Ber- mudas, excepting possibly Scyllarus sculptus. The. specimen figured by Lamarck in the Encyclopédie, and subsequently de- scribed by Milne-Edwards, seems to have been “without a home,” nor have I been able to trace the species from the writ- ings of later authors. I am, therefore, not in a position to say whether the species is strictly Bermudian or not. ;

The remarkable fact connected with the Bermudian Crus- tacea is the appearance of three species of Macrurans which had hitherto been recorded only from the Pacific. These are Palemonella tenwipes, described by Dana from the Sooloo Sea, Palemon affinis, and Penus velutinus, the last a species also first described by Dana. It is remarkable that the only species of Paleemonella other than P. tenwipes is likewise an inhabitant of the Sooloo Sea. I am wholly at a loss how to account for the occurrence of these Pacific types at the Ber- mudas; they may yet be discovered in some intermediate region, and thereby lessen the difficulty in the problem, but for the time being their presence must be considered a zoogeo- graphical knot to be cut. The absence of the common Palamon vulgaris, as well as of the principal crustaceans of the Eastern United States, excepting the more southerly forms, is strik- ingly noticeable. Alpheus avarus is a Eurafrican form ; Pachygrapsus transversus has been noted also from Australia.

The insect fauna (including here also the spiders) of the Ber- mudas is distinguished more by negative features than by positive ones; it is eminently deficient. It is not yet known in its full details, but sufficiently so to show that it is mainly a combination of Neotropical (West Indian and South Ameri- can) and Holarctic (North American) elements. And here we are presented with the significant fact that the insects proper

92 THE BERMUDA ISLANDS.

or fliers are essentially forms common to temperate United States, while the non-fliers or arachnids are more nearly trop- ical or sub-tropical forms, or such as have required drift material to transport them to their present habitation. The former have evidently been carried across the interposing arm of the sea in the manner of the rarer birds—i.e., through the instrumentality of storms. Dr. P. R. Uhler, who has kindly looked over our collections of Orthoptera, Neuroptera, etc., in- forms us that strong winds blowing off the mainland of Mary- land and Virginia carry countless numbers of nearly all kinds of insects out over the ocean, and that those that are dropped into the sea are “returned to the shores by the tides and piled up in windrows along the beaches. Among these we have often found the half-drowned dragon flies mixed in with the thick piles of beetles, bugs, wasps, and flies which stretched along the line of the retreating tide.” That many thus wind- swept reach to distances at least as remote as the Bermudas there can be no question.

We observed during our brief sojourn but four butterflies, Danais archippus, Pyramis Atalanta, P. cardui, and Junonia ceenia, all common forms of the United States, and these appear to be nearly all the forms that are usually met with in the islands. Three or four other species of day-fliers have been observed at different times, but they are of such rare occurrence as to barely constitute true elements of the Bermudian fauna. Our beetles were limited to some five or six species, which Dr. Horn has kindly determined for me to be Ligyrus tumulosus, L. gib- bosus, Agonoderus lineola, Cicindela tortuosa, and Opatrinus anthracinus, forms common to Cuba and the Southern United States. A number of other species of Coleoptera have been collected in the islands, but I am not aware that they have as yet been carefully determined.

From the list of Orthoptera, Pseudoneuroptera, and Dermop- tera which Dr. Uhler has prepared for me it will be seen that they represent types which are included in the United States fauna of the region between Cape Cod and Florida. Dr.

RELATIONSHIP OF THE FAUNA. 93

Uhler calls attention to the significant fact that two of the Pseudoneuropters, Mesothemis longipennis and Lestes unguiculata, are freshwater types, whose larval condition is dependent upon the existence of fresh, or but mildly brackish, waters. The Bermudian earwig (Labidura riparia—Forficula gigantea) is a species recently introduced into the Eastern United States from the Mediterranean region.

Prior to 1888 there were but six species of spiders recorded from the Bermudas, of which three were described as peculiar by Blackwall—Salticus diversus, Xysticus pallidus, and Epeira gracilipes. To this number we now add eleven additional forms, one of which, Lycosa Atlantica of Marx, proves to be new. Dr. Marx, of Washington, has kindly determined all of our forms, and his notes on species appear on another page. The thirteen species which are not peculiar to the Bermudas are the following :

Loxosceles rufescens, . W. Indies, Florida, Europe, Asia,

Africa, Madeira, Canaries, Cape Verde Islands.

Heteropoda venatoria, . Cosmopolitan.

Filistata depressa, , Southern United States.

Uloborus Zosis, . 3 W. Indies, Florida, S. Amer., Africa, Asia, S. Helena.

Nephila clavipes, . : 8S. United States, 8. and C. America.

Epeira caudata, . ; United States.

Epeira labyrinthea, . N. and 8. America (to Magellan), W. Indies.

Theridium tepidariorum, America, Europe, Azores, 8. Helena.

Argyrodes nephile, . United States, Guiana, Peru.

Pholcus tipuloides, .. Samoa.

Dysdera crocata, . ; U. S., Europe, Azores, Canaries, 8. Helena.

Menemerus Paykullit, . Cosmopolitan ?

Menemerus melanognathus, America, Europe, Africa, Canaries, ' Cape Verde L., S. Helena.

94 THE BERMUDA ISLANDS.

The remarkably broad and somewhat indiscriminate distri- bution of most of these species shows almost beyond doubt that they have been principally or largely transported through the agencies of commerce. They, therefore, throw but little light upon the subject of zoogeography, although it is interest- ing to find that such a large number of forms can so readily accommodate themselves to the varied conditions of climate, and of the surroundings generally, which the different countries present. The proportion of peculiar forms is greater than we should have expected to find in a region which is in such fre- quent communication with the mainland, and is supposed to be of comparatively recent origin. But, as has already been seen, there are good grounds for believing that the islands are more ancient than they are generally considered to be—or, at least, that their fauna is. Mr. Bollman has de- termined four species of myriapods in our collections, one of which, a Spirobolus, is apparently peculiar to the islands. Of the remaining forms, as far as it has been possible to determine from imperfect specimens, one of the species is from the Azores, another from Europe, and the third from the United States. Of course the number of species collected is not sufficiently great to give positive values in the matter of distribution.

Of the lower groups of animals, such as the sponges, corals, and echinoderms, we have principally Antillean and Floridian types represented. That this should be the case, more par- ticularly with the reef-building corals, stands to reason. It is less easy to account for the large number of peculiar or new forms among the holothurians, unless it be on the assumption of antiquity. But they may yet be discovered elsewhere, in the West Indies, although if they existed in the Bahamas, where we should naturally expect to look for them, they could scarcely have failed to attract the eyes of the different natural- ists who have from time to time visited the islands. They are in the Bermudas about the most conspicuous objects on the coral sands.

RELATIONSHIP OF THE FAUNA. 95

In summarizing the general features of the Bermudian fauna as they have been passed in review in the preceding pages the following broad conclusions and facts present them- selves :

1. The Bermudian fauna is essentially a wind-drift and cur- rent-drift fauna, whose elements have been received in prin- cipal part from the United States and the West Indies. The aquatic animals are overwhelmingly Antillean in character, while the animals of the air—birds and insects—are as over- whelmingly North American.

2. Some portion of the fauna appears to have been derived (through the agency of the return Atlantic current) from the west coast of Eurafrica (including the African Islands), or even from the Azores, while probably but few forms, if any, were given to those regions by the Bermudas.

3. The large proportion of peculiar forms among the terres- trial Mollusca more particularly,and somewhat less soamong the arachnids and echinoderms, renders it probable that this fauna is in part of considerable antiquity, and that some of its ele- ments have been developed from a fauna pre-existent in the region when the present physical conditions had not yet been established. This conclusion is supported by the fact that the predecessor of a group of Pulmonata now peculiar to the islands is found fossil or sub-fossil in the rock of these islands.

4. Certain marked élements of the Bermudian fauna are of a distinctively Pacific type—Mollusca, Crustacea—but it seems impossible at the present time to explain this mixed relation- ship.

5. The currental water which separates the United States from the Bermudas proves a practically insuperable barrier to the direct passage of marine animals from the one region to

96 THE BERMUDA ISLANDS.

the other ; hence, the forms of the Eastern United States, except in so far as they may be also members of the southern fauna, are almost entirely absent-from the Bermudas.

6. Most of the temperate-American element of the Ber- mudian fauna owes its establishment on the islands to acci- dental causes—storm-winds ; the tropical (Neotropical element) is, on the other hand, the expression of slow but steady diffusion.

7. Neotropical elements largely preponderate in the perma- nent or resident fauna of the islands.

8. An arm of the sea may be as insuperable a barrier to the passage of marine animals as it would be to the animals of the land; caution is hence necessary in the discussion of conti- nental and oceanic changes or stability as affecting animal distribution.

‘HUYOHS HLNOS AHL

Vi

ZOOLOGY OF THE BERMUDAS.

The following notes on the zoology of the Bermudas are based on personal observations, and on collections made dur- ing a brief sojourn on the islands during the past summer, in company with a class of students from the Academy of Natural Sciences. But little systematic work, other than that in the departments of ornithology, ichthyology, and botany, had hitherto been done in this remarkably interesting, and typi- cally oceanic, island group, and it was thought that a more critical survey might bring out facts of general interest to the zoological student, and throw some additional light upon the intricate subject of zoogeography. In the results obtained I have not been disappointed. The exuberance of animal life has yielded much that has proved to be new to the systematist, while certain remarkable peculiarities in the distribution of a number of well-known types of animals open up vistas in geo- graphical distribution which appear to me at present to recede into darkness, and, perhaps, tend to draw only more closely the veil over this mysterious subject.

The specimens noted or described in the following pages were largely obtained through dredgings, which were carried on as well in the outer water as in the smaller interior sounds and lagoons. As might have been anticipated the greatest profusion of animal life was found on the edge of the growing reef itself, the shoals surrounding the cluster of rocks on the northern barrier known as the North Rock. The wealth of forms occurring here almost transcends belief; unfortunately, the limited time at our command and the state of the weather

98 THE BERMUDA ISLANDS.

prevented more than a cursory exammation of this locality, which is made comfortable for collecting and wading during a partial exposure above water of some three hours. All the dredgings were confined to depths within 16 fathoms, which also represents the greatest sounding made by us in the lagoons.

ACTINOZOA.

The true stone corals of the Bermudas are comprised, so far as we now know, in some twenty-five species, the greater number of which are represented by identical forms in the Bahaman or West Indian seas. The genera thus far indicated are Oculina, Mycedium, Astrea, Siderastrea, Porites, Isophyllia, Mxandrina, aud Diploria. The genus Madrepora, one of the commonest of the Bahaman and Floridian corals, appears to be absent. On the south and east side of the island group the outer margin of the growing reef, largely covered by a serpuline and ver- metus growth, approaches to within a few hundred feet of the shore, where it breaks the inflowing surf into a white crest. Within the line of these breakers the depth of water is in places as much as ten or twelve fathoms. The brain coral (Diploria) and various gorgonians develop here in great profu- sion, the huge yellow masses of the former appearing almost everywhere at depths of from ten to twenty feet. Vast growtlis of millepore also cover the shallower bottoms, presenting in the ensemble a wonderful garden of animal development. This profusion of coral growth is, however, surpassed on the north side, where the reef recedes to a distance of some eight or nine miles from the island-shores, enclosing an extensive body of water whose depth is in general about eight or ten fathoms, and more rarely twelve fathoms. Much the same coral growth is indicated here as on the south side, the large brain-corals preponderating by their masses. While, probably, the greatest profusion of animal life is really met with on the actual edge of the growing reef, this does not appear to be the case with the corals themselves. At any rate, I was unable to satisfy myself that there was any marked difference to be ob-

ZOOLOGY OF THE BERMUDAS. 99

served between the marginal growth and that which extends gradually backward from the margin into deep water. In- deed, as far as the brain-corals themselves are concerned, it appeared to me that their largest masses were to be found some distance within the bounding reef, and consequently be- yond the breaking action of the surf. This condition is again shown in the comparatively quiet and sheltered waters of Cas- tle Harbor, where portions of the platform-bottom may be said to constitute one almost connected mosaic of huge Diplorias. In so far, therefore, the Bermudas differ from the greater num- ber of coral islands, in which, as is commonly stated, there is a marked deficiency in the coral growth within the bounding area, and an equally marked luxuriance on the crest and outer slope of the reef.

In most places the largest corals do not come nearer than a foot or two feet of the surface of the water, the massive brain- corals rarely appearing in water of less depth than five or six feet. But in the shallows off the North Rock we found Porites astreoides almost at the surface in low water, and just off the entrance to Harrington Sound, on the north shore, Sideras- trea galaxea was covered by only about two inches of water. The borders of Harrington Sound are largely overgrown with species of Isophyllia, which likewise approach to within a short distance of the surface. In the greater depths of the Sound we found only Oculina, down to ten fathoms, the dredge-net being frequently caught and reversed by their ramose stems; beyond ten fathoms the dredge usually came up empty.

The following species were obtained by us:

Mycedium fragile, Dana.

Two specimens. North Rock? Oculina diffusa, Lamk.

Harrington Sound.

Oculina varicosa, Lesueur. Harrington Sound.

Oculina pallens, Ehrenberg. Harrington Sound.

100 THE BERMUDA ISLANDS.

I feel satisfied that this species is identical with the preced- ing, the same stock bearing what might be considered to be typical representatives of both forms.

The amount of variation in the disposition of the calyces, as well as in their individual shape, is very great in this genus, and I am by no means sure that two or three of the other forms of Oculina here enumerated represent anything more than varietal modifications. Pourtalés, in his illustrations of the corals of the Florida reefs (Mem. Mus. Comp. Zoology, VII, plates I and II) correctly refers, it seems to me, both types to a single species (O. varicosa).

Oculina speciosa, Edwards and Haime.

Harrington Sound.

Oculina recta, Quelch.

One specimen, from Harrington Sound, which agrees in the characters of the species from St. Thomas (Quelch, Challenger Reports, Zoology, XVI, p. 51). The species does not appear to have been hitherto observed in the Bermudian waters. Oculina coronalis, Quelch.

Harrington Sound. First described from the Bermudas (Challenger Reports, Zoology, XVI, p. 49.)

Quelch, in his report on the reef-building corals of the Challenger (op. cit., pp. 9 and 49), enumerates as an additional member of the Bermudian fauna the Oculina Bermudiana of Duchassaing and Michelotti. I have been unable to find any- thing in the description or figures furnished by these authors (Supplément au Mémoire sur les Coralliaires des Antilles, p. 162, pl. IX, figs. 1, 2—Memorie della Reale Accad. Seienze di Torino, Ser. Sec., XXIII, 1866) to distinguish their species from Oculina speciosa, nor doesit appear to me to be distinct. The characters upon which the form is separated are exceedingly trivial, and well within the amount of variability which is presented by individual specimens of nearly all the species of Oculina. I further believe that O. coronalis, and possibly also O. recta, will have to be united with O. speciosa.

ZOOLOGY OF THE BERMUDAS. 101

Isophyllia australis? Edwards and Haime.

Three specimens from the North Rock, doubtfully indenti- fied with this species. Isophyllia fragilis? Dana.

Iam unable to satisfy myself as to the positive existence of this species in Bermuda, although Quelch refers to a single specimen having been obtained there by the Challenger party. This authority doubtfully refers one of the forms figured by Pourtalés (op. cit., pl. VII, fig. 3) as I. dipsacea to Dana’s species, but from an examination of a number of Bermudian specimens which agree absolutely with Pourtalés’s figure I am fairly convinced that this identification is incorrect. The specimens do certainly not agree sufficiently with Dana’s de- scription, and if they are not the types of a distinct species, then they represent probably only a certain phase of develop- ment of I. dipsacea, as is indicated by Pourtalés.

Isophyllia dipsacea, Dana.

Three specimens, from Castle Harbor. Isophyllia strigosa, Duchassaing and Michelotti

A number of specimens, from Harrington Sound, which agree with the description of this species. I am doubtful as to the species being distinct from Isophyllia dipsacea; possibly, however, some of the varieties (so-called) of the latter species figured by Pourtalés are really members of this species. Its principal distinguishing characters appear to be the thinner and more irregular septa, and the terminal cleft that indents or separates the septa of opposing calyces where they cross the common wall. It also presents a more bristling appearance than I. dipsacea.

Isophyllia Guadeloupensis, Portalés.

One specimen. This appears to be a good species, although by Quelch it is referred to Isophyllia strigosa.

In addition to these forms Quelch enumerates Jsophyllia (Symphyllia) marginata, I. cylindrica, and I. Knoxi, all of Duchassaing and Michelotti, as having been obtained at the

102 THE BERMUDA ISLANDS.

Bermudas, but I have failed to detect any specimens among our collections which can be confidently referred to these species. On the other hand, I find one or two forms which I have not yet been able to identify with any described forms. Siderastrea galaxea, Ellis and Solander.

Abundant on the shoals of Gallows Island, near the mouth of Flatts Inlet, where the colonies come to within about two inches of the surface; also on the borders of Harrington Sound. Porites clavaria, Lamk.

Two specimens, dredged in Harrington Sound.

Porites astreaides, Lamk.

We found this species very abundantly along the outer reef, especially on the flats of the North Rock, where it is the domi- nant form of coral. The species appears to have been over- looked by the Challenger party, and indeed, the only reference that I have been able to find indicating the occurrence of this common West Indian form among the Bermudas is contained in Mr. Rathbun’s list of the species of Porites in the United States National Museum (Proc. U.S. National Museum, 1887, p. 354).

Meandrina labyrinthica, Ellis and Solander.

Three specimens, from the North Rock. Meandrina strigosa, Dana.

This form is represented by large, sub-globose specimens, one of which, obtained through purchase, and probably from Castle Harbor, has an exceedingly attenuated base of attach- ment. The corallum is thus openly turbinate, or even pedicu- late, and exhibits in its regular scalariform outline the succes- sive stages of outward development.

Diploria cerebriformis, Lamk.

This species is exceedingly abundant in the shoals lying to the leeward of the marginal reef, where its huge hemispheri- cal or reniform masses of bright orange, measuring as much as four or five feet in diameter, can be distinctly seen through

ZOOLOGY OF THE BERMUDAS. 103

the transparent waters at depths of from six to fifteen or twenty feet. I cannot say how much further down the species extends. It is equally abundant in Castle Harbor, where it is largely instrumental in building out the shore-platform which, at a moderate distance from the shore, descends vertically into deeper water. When attached by a contracted base, the brain- coral may be readily removed from its moorings; but where the base is largely coextensive with the under-surface of the corallum the difficulties of removal are very great, necessitat- ing much undercutting with a chisel. The largest specimen obtained by us measured about 28 inches across; our efforts to dislodge a specimen about four feet in diameter proved un- successful.

Diploria Stokesi, Edwards and Haime.

We obtained a number of specimens of this species in Castle Harbor, and through presentation ; for the latter my thanks are due to Miss A. Peniston, of Peniston’s. The habitat of the species, as far as I am aware, has not hitherto been noted. Edwards and Haime in their description of the species (Hist. Nat. des Coralliaires, II, p. 408, pl. D, fig. 3) state “ Patrie incon- nue.” I believe it may be assumed that this species is the form described and figured by Knorr as Madrepora labyrinthi- formis (Delicitz Naturzx Selcectx, I, p. 18, Pl. A 4, fig. 1). In our collections we have a closely related, and possibly identical, species, which assumes a ring form, and in which the peculiar calycular hollows of D. Stokesi run out into parallel transverse grooves on the inner side of the ring.

ALCYONARIA.

The gorgonians are abundant in the waters inside of the bounding reef, whence nearly all our specimens were obtained. A few were nipped up on the south side of Castle Harbor, and at the passage way conducting from the north into that body of water.

Rhipidogorgia flabellum, Valenciennes,

The purple variety of this species is abundant more par-

ticularly in the northern waters, both near the outer reef and

104 THE BERMUDA ISLANDS.

on the shallows known as Devonshire Flats. We failed to obtain any of the yellow forms, and I am not positive that this variety has ever been found at the Bermudas.

Gorgonia (Plexaura) purpurea, Pallas.

Gorgonia (Plexaura) flexuosa, Lamouroux.

This species, of which we obtained several specimens, is, I believe, without doubt the Gorgonia anguiculus of Dana (U.S. Exploring Expedition, Zoophytes, p. 668). It is referred to under Lamouroux’s name as a member of the Bermudian fauna in Dana’s “Corals and Coral Islands,” p. 114, 1872. - Gorgonia (Plexaura) homomalla, Esper.

Gorgonia (Plexaura) multicauda, Lam.

Gorgonia crassa, Ellis and Solander.

G. vermiculata, Edwards and Haime.

The exact limitations and synonymy of this species are difficult to make out, but as far as my studies have permitted

_me to analyze the forms above indicated from the rather in- sufficient or deficient descriptions that have been furnished by their authors, they appear to represent an identical form. As such I have accordingly referred them in this list.

Gorgonia (Plexaura) dichotoma, Esper.

A single specimen, measuring about a foot and three-quar- ters in height, with the main stems somewhat over a half-inch in diameter.

Gorgonia (Eunicea) pseudo-antipathes, Lam.

One much branched specimen, and another, slightly differing, which appears to belong to the same species. Pterogorgia acerosa, (?) Pallas.

A single specimen of a large Pterogorgia, entirely stripped of ceenenchyma, and measuring about two and a-half feet in height, was obtained through purchase at the Crawl. The axial skeleton is yellowish, or of the color of earth. The terete branches are much more broadly spreading than in P. setosa, and unite into a common basal stalk which is upwards of two inches in thickness. The pinnules are very numerous,

ZOOLOGY OF THE BERMUDAS. 105

exceedingly slender, and pendulous, giving to the whole organism the decided appearance of a weeping-willow.

I have not been able to satisfy myself as to the exact affinities of this species. It appears to differ broadly from the common purple sea-feather of the West Indies, and does not have the depressed branches which are assumed for Esper’s Pterogorgia acerosa. It is, however, with little doubt one of the forms that are included by Pallas in his Gorgonia acerosa (Quercus marina Theophrasti), and may be the one that is referred to by Milne-Edwards as Pterogorgia Sloanei.

Of the species of gorgonians above enumerated Dana indi- cates Rhipidogorgia flabellum, Gorgonia fleruosa, G. homomalla, and G. crassa as coming from the Bermudas (“Corals and Coral Islands,” p. 114). I find no mention in any more recent work of the occurrence there of either Gorgonia pseudo-anti- pathes or G. dichotoma. On the other hand, we failed to obtain the Pterogorgia Americana mentioned by Dana.

ACTINIARIA.

For the following contribution to the “ Actinology of the Ber- mudas” I am indebted to Prof. J. Playfair McMurrich, who has carefully examined and studied all the specimens contained in our collection. These were not very numerous, but still sufficiently so to present a number of interesting points in special morphology and geographical distribution. The