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SEASIDE STUDIES 



NATURAL HISTORY, 



BY 



ELIZABETH C. AGASSIZ 

AND 

ALEXANDER AGASSIZ. 



MARINE ANIMALS OF MASSACHUSETTS BAY, 
RADIATES. 




BOSTON: 
TICK NOR AND FIELDS. 

1865. 






5 

o 



Entered according to Act of Congress, in the year 1865. by 

ALEXANDER AGAS8IZ, 
in the Clerk s Office of the District Court for the District of Massachusetts. 



UNIVERSITY PRESS: 

WELCH, BIG BLOW, AND COMPANY, 

CAMBRIDGE. 



THIS LITTLE BOOK 

IS AFFECTIONATELY DEDICATED BY THE AUTHORS TO 

PROFESSOR L. AGASSIZ, 

WHOSE PRINCIPLES OF CLASSIFICATION HAVE BEEN THE MAIN 
GUIDE IN ITS PREPARATION. 



PREFACE. 



THIS volume is published with the hope of supplying 
a want often expressed for some seaside book of a popu 
lar character, describing the marine animals common to 
our shores. There are many English books of this kind ; 
but they relate chiefly to the animals of Great Britain, 
and can only have a general bearing on those of our own 
coast, which are for the most part specifically different 
from their European relatives. While keeping this ob 
ject in view, an attempt has also been made to present 
the facts in such a connection, with reference to prin 
ciples of science and to classification, as will give it in 
some sort the character of a manual of Natural History, 
in the hope of making it useful not only to the general 
reader, but also to teachers and to persons desirous of 
obtaining a more intimate knowledge of the subjects 
discussed in it. With this purpose, although nearly all 
the illustrations are taken from among the most com 
mon inhabitants of our bay, a few have been added 
from other localities in order to fill out this little sketch 
of Radiates, and render it, as far as is possible within 
such limits, a complete picture of the type. 



VI PREFACE. 

A few words of explanation are necessary with ref 
erence to the joint authorship of the book. The draw 
ings and the investigations, where they are not referred 
to other observers, have been made by MR. A. AGASSIZ, 
the illustrations having been taken, with very few ex 
ceptions, from nature, in order to represent the animals, 
as far as possible, in their natural attitudes ; and the 
text has been written by MRS. L. AGASSIZ, with the 
assistance of MR. AGASSIZ S notes and explanations. 

CAMBRIDGE, May, 18G5. 



CONTENTS 



PAGE 
ON RADIATES IN GENERAL ....... 1 

GENERAL SKETCH OF THE POLYPS ...... 5 

ACTINOIDS .......... 7 

MADREPORIANS ......... 16 

HALCYONOIDS . . . . . . . . . .19 

GENERAL SKETCH OF ACALEPHS 21 

CTENOPHOR^: .......... 26 

EMBRYOLOGY OF CTENOPHOR.E ...... 34 

DISCOPHOR.E .......... 37 

HYDROIDS .......... 49 

MODE OF CATCHING JELLY-FISHES . . . . . .85 

ECHINODERMS ......... 91 

HOLOTHURIANS .......... 95 

ECHINOIDS .......... 101 

STAR-FISHES 108 

OPHIURANS . . . . . . . . ... 115 

CRINOIDS . . . . . . . . . .120 

EMBRYOLOGY OF ECHINODERMS . . . . . . 123 

DISTRIBUTION OF LIFE IN THE OCEAN ..... 141 

SYSTEMATIC TABLE ........ 152 

INDEX . 154 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



ON EADIATES IN GENERAL. 

IT is perhaps not strange that the Radiates, a type of animals 
whose home is in the sea, many of whom are so diminutive in size, 
and so light and evanescent in substance, that they are hardly to 
be distinguished from the element in which they live, should have 
been among the last to attract the attention of naturalists. Nei 
ther is it surprising to those who know something of the history of 
these animals, that when the investigation of their structure was 
once begun, when some insight was gained into their complex life, 
their association in fixed or floating communities, their wonder 
ful processes of development uniting the most dissimilar individ 
uals in one and the same cycle of growth, their study should have 
become one of the most fascinating pursuits of modern science, 
and have engaged the attention of some of the most original in 
vestigators during the last half century. It is true that from 
the earliest days of Natural History, the more conspicuous and 
easily accessible of these animals attracted notice and found their 
way into the scientific works of the time. Even Aristotle de 
scribes some of them under the names of Acalephae and Knidae, 
and later observers have added something, here and there, to our 
knowledge on the subject ; but it is only within the last fifty 
years that their complicated history has been unravelled, and the 
facts concerning them presented in their true connection. 

Among the earlier writers on this subject we are most indebted 
to Rondelet, in the sixteenth century, who includes some account 
of the Radiates, in his work on the marine animals of the Medi 
terranean. His position as Professor in the University at Mont- 
i 



Z MARINE ANIMALS OF MASSACHUSETTS BAY. 

pelier gave him an admirable opportunity, of which he availed 
himself to the utmost, for carrying out his investigations in this 
direction. Seba and Klein, two naturalists in the North of Eu 
rope, also published at about this time numerous illustrations of 
marine animals, including Radiates. But in all these works we 
find only drawings and descriptions of the animals, without any 
attempt to classify them according to common structural features. 
In 1776, 0. F. Miiller, in a work on the marine and terrestrial 
faunae of Denmark, gave some admirable figures of Radiates, 
several of which are identical with those found on our own 
coast. Cavolini also in his investigations on the lower marine 
animals of the Mediterranean, and Ellis in his work upon those 
of the British coast, did much during the latter half of the past 
century to enlarge our knowledge of them. 

It was Cuvier, however, who first gave coherence and precision 
to all previous investigations upon this subject, by showing that 
these animals are united on a common plan of structure expres 
sively designated by him under the name Radiata. Although, 
from a mistaken appreciation of their affinities, he associated 
some animals with them which do not belong to the type, and 
have since, upon a more intimate knowledge of their structure, 
been removed to their true positions ; yet the principle intro 
duced by him into their classification, as well as into that of the 
other types of the animal kingdom, has been all important to 
science. 

It was in the early part of this century that the French began 
to associate scientific objects with their government expeditions. 
Scarcely any important voyage was undertaken to foreign coun 
tries by the French navy which did not include its corps of nat 
uralists, under the patronage of government. Among the most 
beautiful figures we have of Radiates, are those made by Sa- 
vigny, one of the French naturalists who accompanied Napoleon 
to Egypt ; and from this time the lower marine animals began 
to be extensively collected and studied in their living condition. 
Henceforth the number of investigators in the field became more 
numerous, and it may not be amiss to give here a slight account 
of the more prominent among them. 

Darwin s fascinating book, published after his voyage to the 



ON RADIATES IN GENERAL. 6 

Pacific, and giving an account of the Coral islands, the many 
memoirs of Milne Edwards and Haime, and the great works of 
Quoy and Gaimard, and of Dana, are the chief authorities upon 
Polyps. In the study of the European Acalephs we have a long 
list of names high in the annals of science. Eschscholtz, Peroii 
and Lesueur, .Quoy and Gaimard, Lesson, Mertens, and Huxley, 
have all added : largely to our information respecting these ani 
mals, their various voyages having enabled them to extend their 
investigations "Over a wide field. No less valuable have been the 
contributions of Kolliker, Leuckart, Gegenbaur, and Yogt, who 
in their frequent excursions to the coasts of Italy and France 
have made a special study of the Acalephs, and whose descrip 
tions have all the . vividness and freshness which nothing but 
familiarity with the living specimens can give. Besides these, 
we have the admirable works of Yon Siebold, of Ehrenberg, 
the great interpreter Gf the microscopic world, of Steenstrup, 
Dujardin, Dalyell, Forbes, Allman, and Sars. Of these, the four 
latter were fortunate in having their home on the sea-shore with 
in reach of the objects of their study, so that they could watch 
them in their living condition, and follow all their changes. The 
charming books of Forbes, who knew so well how to popularize 
his instructions, and i present scientific results under the most at 
tractive form, are well known to English readers. But a word on 
the investigations of Sars may not be superfluous. 

Born near the coast of Norway, and in early life associated 
with the Church, -his passion for Natural History led him to em 
ploy all his spare time in the study of the marine animals im 
mediately about him, and his first papers on this subject attracted 
so much attention, that he was offered the place of Professor at 
Christiania, and henceforth devoted himself exclusively to scien 
tific pursuits, \and especially to the investigation of the Acalephs. 
He gave us the key to the almost fabulous transformations of 
these animals, and opened a new path in science by showing the 
singular phenomenon of the so-called " alternate generations," 
in, which the different phases of the same life may be so distinct 
and seemingly so disconnected that, until we find the relation 
between them, we seem to have several animals where we have 
but one. 



4 MARINE ANIMALS OF MASSACHUSETTS BAY. 

To the works above mentioned, we may add the third and 
fourth volumes of Professor Agassiz s Contributions to the Nat 
ural History of the United States, which are entirely devoted to 
the American Acalephs. 

The most important works and memoirs concerning the Echino- 
derms are those by Klein, Link, Johannes Miiller, Jiiger. Des- 
moulins, Troschel, Sars, Savigny, Forbes, Agassiz, and Lutken, 
but excepting those of Forbes and Sars, few of these observations 
are made upon the living specimens. It may be well to mention 
here, for the benefit of those who care to know something more 
of the literature of this subject in our own country, a number of 
memoirs on the Radiates of our coasts, published by the various 
scientific societies of the United States, and to be found in their 
annals. Such are the papers of Gould, Agassiz, Leidy, Stimpson, 
McCrady, Clark, A. Agassiz, and Verrill. 

One additional word as to the manner in which the subjects 
included in the following descriptions are arranged. We have 
seen that Cuvier recognized the unity of plan in the structure 
of the whole type of Radiates. All these animals have their 
parts disposed around a common central axis, and diverging from 
it toward the periphery. The idea of bilateral symmetry, or the 
arrangement of parts on either side of a longitudinal axis, on 
which all the higher animals are built, does not enter into their 
structure, except in a very subordinate manner, hardly to be per 
ceived by any but the professional naturalist. This radiate struc 
ture being then common to the whole type, the animals compos 
ing it appear under three distinct structural expressions of the 
general plan, and according to these differences are divided into 
three classes, Polyps, Acalephs, and Echinoderms. With these 
few preliminary remarks we may now take up in turn these dif- 
erent groups, beginning with the lowest, or the Polyps.* 

* It is to be regretted that on account of the meagre representations of Polyps on 
our coast, where the coral reefs, which include the most interesting features of Polyp 
life, are entirely wanting, our account of these animals is necessarily deficient in vari 
ety of material. When we reach the Acalephs or Jelly-Fishes, in which the fauna of 
our shores is especially rich, we shall not have the same apology for dulness ; and it 
will he our own fault if our readers are not attracted by the many graceful forms to 
which we shall then introduce them. 



Fig. i. 




GENERAL SKETCH OF THE POLYPS. 



GENERAL SKETCH OF THE POLYPS. 

BEFORE describing the different kinds of Polyps living on our 
immediate coast, we will say a few words of Polyps in general 
and of the mode in which the structural plan common to all 
Radiates is adapted to this particular class. In all Polyps the 
body consists of a sac divided by vertical partitions (Fig. 1.) into 
distinct cavities or chambers. These parti- 
tions are not, however, all formed at once, but 
are usually limited to six at first, multiplying 
indefinitely with the growth of the animal in 
some kinds, while in others they never in 
crease beyond a certain definite number. In 
the axis of the sac, thus divided, hangs a 
smaller one, forming the digestive cavity, 
and supported for its whole length by the six 
primary partitions. The other partitions, though they extend 
more or less inward in proportion to their age, do not unite 
with the digestive sac, but leave a free space in the centre be 
tween their inner edge and the outer wall of the digestive sac. 
The genital organs are placed on the inner edgCvS of the partitions, 
thus hanging as it were at the door of the chambers, so that 
when hatched, the eggs naturally drop into the main cavity of 
the body, whence they pass into the second smaller sac through 
an opening in its bottom or digestive cavity, and thence out 
through the mouth into the water. In the lower Polyps, as in 
our common Actinia for instance, these organs occur on all the 
radiating partitions, while among the higher ones, the Halcy- 
onoids for example, they are found only on a limited number. 
This limitation in the repetition of identical parts is always found 
to be connected with structural superiority. 

The upper margin of the body is fringed by hollow tentacles, 
each of which opens into one of the chambers. All parts of the 
animal thus communicate with each other, whatever is intro 
duced at the mouth circulating through the whole structure, 



Fig. 1. Transverse section of an Actinia. (Agassiz.} 



6 MARINE ANIMALS OF MASSACHUSETTS BAY. 

passing first into the digestive cavity, thence through the opening 
in the bottom into the main chambered cavity, where it enters 
freely into all the chambers, and from the chambers into the ten 
tacles. The rejected portions of the food, after , the process of 
digestion is completed, return by the same road arid" are thrown 
out at the mouth. 

These general features exist in all Polyps, and Whether they 
lead an independent life as the Actinia, or are; combined in com 
munities, like most of the corals and the Halcyonpids, ; whether the 
tentacles are many or few ; whether the partitions extend to a 
greater or less height in the body ; whether .they contain limestone 
deposit, as in the corals, or remain soft thrpughout life as the sea- 
anemone, the above description applies to them all, while the 
minor differences, either in the tentacles or -in the; form, size, color, 
and texture of the body, are simply modifications of this structure, 
introducing an infinite variety into the class, and .breaking it up 
into the lesser groups designated as orders, families, genera, and 
species. Let us now look at some of the divisions thus estab 
lished. . -- . ,<; > t-v 

The class of Polyps is divided into three orders, the Halcy- 
onoids, the Madreporians, and the Actinoids. Of the lowest 
among these orders, the Actinoid Polyps, our -Actinia or sea-ane 
mone is a good example. They remain soft .-through life, having 
a great number of partitions and consequentty.a great number of 
tentacles, since there is a tentacle corresponding to every cham 
ber. Indeed, in this order the multiplication of tentacles and 
partitions is indefinite, increasing during the whole life of the 
animal with its growth ; while we shall see; that in some of the 
higher orders the constancy and limitation in the number of these 
parts is an indication of superiority, being accompanied by a 
more marked individualization of the different functions. 

Next come the Madreporians, of which our Astrangia, to be 
described hereafter, may be cited as an example. In this group, 
although the number of tentacles still continues to be large, they 
are nevertheless more limited than in the Actinoids ; but their 
characteristic feature is the deposition of limestone walls in the 
centre of the chambers formed by the soft partitions, so that all 
the soft partitions alternate with hard ones. The tentacles, al- 



ACTINOIDS. 7 

ways corresponding to the cavity of the chambers, may be there 
fore said to ride this second set of partitions arising just in the 
centre of the chambers. 

The third and highest order of Polyps is that of the Halcyo- 
noids. Here the partitions are reduced to eight ; the tentacles, 
according to the invariable rule, agree in number with the cham 
bers, but have a far more highly complicated structure than in 
the lower Polyps. Some of these Halcyonoids deposit limestone 
particles in their frame. But the tendency to solidify is not lim 
ited to definite points, as in the Madreporians. It may take place 
anywhere, the rigidity of the whole structure increasing of course 
in proportion to the accumulation of limestone. There are many 
kinds, in which the axis always remains soft or cartilaginous, 
while others, as the so-called sea-fans for instance, well known 
among the corals for their beauty of form and color, are stiff 
and hard throughout. Whatever their character in this respect, 
however, they are always compound, living in communities, and 
never found as separate individuals after their early stages of 
growth. Some of those with soft axis lead a wandering life, 
enjoying as much freedom of movement as if they had an indi 
vidual existence, shooting through the water like the Pennatulae, 
well known on the California coast, or working their way through 
the sand like the Renilla, common on the sandy shores of our 
Southern States. 



ACTINOIDS. 

Actinia, or Sea-Anemone. (Metridium marginatum EDW.) 

NOTHING can be more unprepossessing than a sea-anemone when 
contracted. A mere lump of brown or whitish jelly, it lies like 
a lifeless thing on the rock to which it clings, and it is difficult to 
believe that it has an elaborate and exceedingly delicate inter 
nal organization, or will ever expand into such grace and beauty 
as really to deserve the name of the flower after which it has been 
called. Figs. 2, 3, 4, and 5, show this animal in its various stages 



8 MARINE ANIMALS OF MASSACHUSETTS BAY. 

of expansion and contraction. Fig. 2 represents it with all its 
external appendages folded in, and the whole body flattened ; in 
Fig. 3, the tentacles begin to steal out, arid the body rises slightly ; 
in Fig. 4, the body has nearly gained its full height, and the ten- 
Fig. 2. Fig. 3. Fig. 4. 




tacles, though by no means fully spread, yet form a delicate 
wreath around the mouth ; while in Fig. 5, drawn in life size, the 

Fig. 5. 




Figs. 2, 3, 4 Actinia in different degrees of expansion. (Ayassiz.) 

Fig. 5. The same Actinia (Metridium marginatum) fully expanded ; natural size. 



METRIDIUM. y 

whole summit of the body seems crowned with soft, plumy fringes. . 
We would say for the benefit of collectors that these animals are 
by no means difficult to find, and thrive well in confinement, 
though it will not do to keep them in a small aquarium with 
other specimens, because they soon render the water foul and . 
unfit for their companions. They should therefore be kept in 
a separate glass jar or bowl, and under such circumstances will 
live for a long time with comparatively little care. 

They may be found in any small pools about the rocks which 
are flooded by the tide at high water. Their favorite haunts, 
however, where they occur in greatest quantity are more difficult 
to reach ; but the curious in such matters will be well rewarded, 
even at the risk of wet feet and a slippery scramble over rocks 
covered with damp sea-weed, by a glimpse into their more crowded 
abodes. Such a grotto is to be found on the rocks of East Point 
at Nahant. It can only be reached at low tide, and then one is 
obliged to creep on hands and knees to its entrance, in order to 
see through its entire length ; but its whole interior is studded 
with these animals, and as they are of various hues, pink, brown, 
orange, purple, or pure white, the effect is like that of brightly 
colored mosaics set in the roof and walls. When the sun strikes 
through from the opposite extremity of this grotto, which is open 
at both ends, lighting up its living mosaic work, and showing the 
play of the soft fringes wherever the animals are open, it would 
be difficult to find any artificial grotto to compare with it in 
beauty. There is another of the same kind on Saunders s Ledge, 
formed by a large boulder resting on two rocky ledges, leaving a 
little cave beneath, lined in the same way with variously colored 
sea-anemones, so closely studded over its walls that the surface 
of the rock is completely hidden. They are, however, to be found 
in larger or smaller clusters, or scattered singly in any rocky fis 
sures, overhung by sea-weed, and accessible to the tide at high 
water. 

The description of Polyp structure given above includes all the 
general features of the sea-anemone ; but for the better explana 
tion of the figures, it may not be amiss to recapitulate them here 
in their special application. The body of the sea-anemone may be 
described as a circular, gelatinous bag, the bottom of which is flat 

2 




10 MARINE ANIMALS OF MASSACHUSETTS BAY. 

and slightly spreading around the margin. (Fig. 2.) The upper 
edge OL this bag turns in so as to form a sac within a sac. (Fig. 
Fig. e. 6.) This inner sac, s, is the stomach or 

digestive cavity, forming a simple open 
space in the centre of the body, with an 
aperture in the bottom, 5, through which 
the food passes into the larger sac, in 
which it is enclosed. But this outer 
and larger sac or main cavity of the 
body is not, like the inner one, a simple open space. It is, on the 
contrary, divided by vertical partitions into a number of distinct 
chambers, converging from the periphery to the centre. These 
partitions do not all advance so far as actually to join the wall of 
the digestive cavity hanging in the centre of the body, but most 
of them stop a little short of it, leaving thus a small, open space 
between the chambers and the inner sac. (Fig. 1.) The eggs 
hang on the inner edge of the partitions ; when mature they 
drop into the main cavity, enter the inner digestive cavity through 
its lower opening, and are passed out through the mouth. 

The embryo bears no resemblance to the mature animal. It is 
a little planula, semi-transparent, oblong, entirely covered with 
vibratile cilia, by means of which it swims freely about in the 
water till it establishes itself on some rocky surface, the end 
by which it becomes attached spreading slightly and fitting 
itself to the inequalities of the rock so as to form a secure basis. 
The upper end then becomes depressed toward the centre, that 
depression deepening more and more till it forms the inner sac, 
or in other words the digestive cavity described above. The open 
mouth of this inner sac, which may, however, be closed at will, 
since the whole substance of the body is exceedingly contractile, 
is the oral opening or so-called mouth of the animal. We have 
seen how the main cavity becomes divided by radiating partitions 
into numerous chambers ; but while these internal changes are 
going on, corresponding external appendages are forming in the 
shape of the tentacles, which add so much to the beauty of the 
animal, and play so important a part in its history. The ten- 
Fig. 6. Vertical section of an Actinia, showing a primary (gr) and a secondary partition g ; o mouth, 
t tentacles, s stomach, // reproductive organs, b main cavity, c openings in partitions, a lower floor, or 
foot. 



METRIDIUM. 



11 



Fig. 7. 



tacles, at first only few in number, are in fact so many extensions 

of the inner chambers, gradually narrowing upward till they 

form these delicate hollow feelers which make a soft downy fringe 

all around the mouth. (Fig. 7.) They do not start abruptly from 

the summit, but the upper margin 

of the body itself thins out to 

form more or less extensive lobes, 

through which the partitions and 

chambers continue their course, 

and along the edge of which the 

tentacles arise. 

The eggs are not always laid in 
the condition of the simple planula 
described above. They may, on the * "; ly - 

contrary, be dropped from the par- Wv 

ent in different stages of develop- ^ 

ment, sometimes even after the tentacles have begun to form, as 
in Figs. 8, 9. Neither is it by means of eggs alone that these 




W 



Fig. 



Fig. 9. 





animals reproduce themselves ; they may also multiply by a pro 
cess of self-division. The disk of an Actinia may contract along 
its centre till the circular outline is changed to that of a figure 8, 
this constriction deepening gradually till the two halves of the 8 
separate, and we have an Actinia with two mouths, each sur 
rounded by an independent set of tentacles. Presently this sepa 
ration descends vertically till the body is finally divided from 

Fig. 7. View from above of an Actinia with all its tentacles expanded ; o mouth, b crescent-shaped 
folds at extremity of mouth, a a folds round mouth, 1 1 1 tentacles. 
Figs. 8, 9. Young Actiuiie in different stages of growth. 



12 MARINE ANIMALS OF MASSACHUSETTS BAY. 

summit to base, and we have two Actiniae where there was origi 
nally but one. Another and a far more common mode of re 
production among these animals is that of budding like corals. 
A slight swelling arises 011 the side of the body or at its base ; 
it enlarges gradually, a digestive cavity is formed within it, tenta 
cles arise around its summit, and it finally drops off from the 
parent and leads an independent existence. As a number of 
these buds are frequently formed at once, such an Actinia, sur 
rounded by its little family, still attached to the parent, may ap 
pear for a time like a compound stock, though their normal mode 
of existence is individual and distinct. 

The Actinia is exceedingly sensitive, contracting the body and 
drawing in the tentacles almost instantaneously at the slightest 
touch. These sudden movements are produced by two powerful 
sets of muscles, running at right angles with each other through 
the thickness of the body wall ; the one straight and vertical, ex 
tending from the base of the wall to its summit ; the other cir 
cular and horizontal, stretching concentrically around it. By 
the contraction of the former, the body is of course shortened ; by 
the contraction of the latter, the body is, on the contrary, length 
ened in proportion to the compression of its circumference. Both 
sets can easily be traced by the vertical and horizontal lines cross 
ing each other 011 the external wall of the body, as in Fig. 5. 
Each tentacle is in like manner furnished with a double set of 
muscles, having an action similar to that described above. In 
consequence of these violent muscular contractions, the water im 
bibed by the animal, and by which all its parts are distended to 
the utmost, is forced, not only out of the mouth, but also through 
small openings in the body wall scarcely perceptible under ordi 
nary circumstances, but at such times emitting little fountains in 
every direction. 

Notwithstanding its extraordinary sensitiveness, the organs of 
the senses in the Actinia are very inferior, consisting only of a 
few pigment cells accumulated at the base of the tentacles. The 
two sets of muscles meet at the base of the body, forming a disk, 
or kind of foot, by which the animal can fix itself so firmly to 
the ground, that it is very difficult to remove it without in 
jury. It is nevertheless capable of a very limited degree of 



RHOD ACTINIA. 13 

motion, by means of the expansion and contraction of this foot- 
like disk. 

The Actinias are extremely voracious ; they feed on mussels 
and cockles, sucking the animals out of their shells. When in 
confinement they may be fed on raw meat, and seem to relish it ; 
but if compelled to do so, they will live on more meagre fare, and 
will even thrive for a long time on such food as they may pick 
up in the water where they are kept. 

Rhodactinia. (Rhodactinia Davisii AG.) 

Very different from this is the bright red Rhodactinia (Fig. 
10), quite common in the deeper waters of our bay, while far 
ther nor tli, in Maine, it occurs at low-water mark. Occasion 
ally it may be found thrown up on our sandy beaches after a 
storm, and then, if it has not been too long out of its native 
element, or too severely buffeted by the waves, it will revive on 
being thrown into a bucket 

f. ? , Fig. 10. 

ot iresn sea-water, expand 
to its full size, and show all 
the beauty of its natural col 
oring. It is crowned with a 
wreath of thick, short tenta 
cles (Fig. 10), and though so 
vivid and bright in color, it 
is not so pretty as the more 
common Actinia marginata, 
with its soft waving wreath of 
plume-like feelers, in compar 
ison to which the tentacles of the Rhodactinia are clumsy and 
slow in their movements. 

All Actiniae are not attached to the soil like those described 
above, nor do they all terminate in a muscular foot, some being 
pointed or rounded at their extremity. Many are nomadic, wan 
dering about at will during their whole lifetime, others live 
buried in the sand or mud, only extending their tentacles beyond 
the limits of the hole where they make their home ; while others 
again lead a parasitic life, fastening themselves upon our larger 

Fig. 10. Rhodactinia Davisii Ag. ; natural size. 




14 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



jelly-fish, the Cyaneae, though one is at a loss to imagine what 
sustenance they can derive from animals having so little solidity, 
and consisting so largely of water. 

ArachnactlS. (Arachnactis brachiolata A. AG.) 



Fig. 11. 




Fig. 12. 




Among the nomadic Polyps is a small 
floating Actinia, called Arachnactis, 
(Fig. 11,) from its resemblance to a 
spider. They are found in great plenty 
floating about during the night, feeling 
their way in every direction by means 
of their tentacles, which are large 
in proportion to the size of the animal, 
few in number, and turned downward 
when in their natural attitude. The 
partitions and the digestive cavity en 
closed between them are short, as will 
be seen in Fig. 11, when compared to 
the general cavity of the body floating 
balloon-like above them. Around the 
mouth is a second row of shorter ten 
tacles, better seen in a younger speci 
men (Fig. 12). This Actinia differs 
from those described above, in having 
two of the sides flattened, instead of 
being perfectly circular. Looked at 
from above (as in Fig. 13) this differ 
ence in the diameters is very percepti 
ble ; there is an evident tendency to 
wards establishing a longitudinal axis. 
In the sea-anemone, this disposition is 
only hinted at in the slightly pointed 
folds or projections on opposite sides of 
the circle formed by the mouth, which 
in the Arachnactis are so elongated as 
to produce a somewhat narrow slit (see 



Fig. 11. 

Fig. 13. 



Arachnactis brachiolata A. Ag., greatly magnified. 
Young Arachnactis seen so as to show the mouth. 



Fig. 12. Young Arachnactis. 



BICIDIUM. 15 

Fig. 13), instead of a circular opening. The mouth is also a 
little out of centre, rather nearer one end of the disk than the 
other. These facts are interesting, as showing that the ten 
dency towards establishing a balance of parts, as between an an 
terior and posterior extremity, a right and left side, is not forgot 
ten in these lower animals, though their organization as a whole 
is based upon an -equality of parts, admitting neither of pos 
terior and anterior extremities, nor of right and left, nor of 
above and below, in a structural sense. This animal also pre 
sents a seeming anomaly in the mode of formation of the 
young tentacles, which always make their appearance at the 
posterior extremity of the longitudinal axis, the new ones being 
placed behind the older ones, instead of alternating with them as 
in other Actiniae. 



Bicidium. (Biddium parasiticum AG.) 

The Bicidium (Fig. 14), our parasitic Actinia, is to be sought 
for in the mouth-folds of the Cyanea, our common large red 
Jelly-fish. In any moderate-sized specimen of the latter from 
twelve to eighteen inches in diameter, we shall be sure to find 
one or more of these parasites, hidden away among the numerous 
folds of the mouth. The body is long and tapering, having an ap 
erture in the extremity, the whole animal being Fig. 14. 
like an elongated cone, strongly ribbed from 
apex to base. At the base, viz. at the mouth 
end, are a few short, stout tentacles. This Ac 
tinia is covered with innumerable little trans 
verse wrinkles (see Fig. 14) , by means of which 
it fastens itself securely among the fluted mem 
branes around the mouth of the Jelly-fish. It 
will live a considerable time in confinement, at 
taching itself, for its whole length, to the vessel 
in which it is kept, and clinging quite firmly if 
any attempt is made to remove it. The general 
color of the body is violet or a brownish red, 
though the wrinkles give it a somewhat mottled appearance. 

Fig. 14. Bicidium parasiticum; natural size. 




16 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 15 



Halcampa. (Halcampa albida Ac.) 

Strange to say, the Actiniae, which live in the mud, are 
among the most beautifully colored of these animals. They 
frequently prepare their home with some care, lining their hole 
by means of the same secretions which give their slimy surface 
to our common Actiniae, and thus forming a sort of tube, into 
which they retire when alarmed. But if undis 
turbed, they may be seen at the open door of 
their house with their many-colored disk and 
mottled tentacles extending beyond the aperture, 
and their mouth wide open, waiting for what the 
tide may bring them. By the play of their ten 
tacles, they can always produce a current of 
water about the mouth, by means of which food 
passes into the stomach. We have said, that 
these animals are very brightly colored, but the 
little Halcampa (Fig. 15), belonging to our coast, 
is not one of the brilliant ones. It is, on the 
contrary, a small, insignificant Actinia, resem 
bling a worm, as it burrows its way through the 
sand. It is of a pale yellowish color, with whitish warts on the 
surface. 




MADREPORIANS. 

Astrangid. (Astrangia Dance AG.) 

IN Figure 16, we have the only species of coral growing 
so far north as our latitude. Indeed, it hardly belongs in 
this volume, since we have limited ourselves to the Radiates of 
Massachusetts Bay, its northernmost boundary being some 
what to the south of Massachusetts Bay, about the shores of 
Long Island, and on the islands of Martha s Vineyard Sound. 
But we introduce it here, though it is not included under our 

Fig. 15. Halcampa albida-, natural size. 




MADREPORIANS. 17 

title, because any account of the Radiates, from which so impor 
tant a group as that of the corals was excluded, would be very 
incomplete. 

This pretty coral of Fig. 10. 

our Northern waters is 
no reef-builder, and does 
not extend farther south 
than the shores of North 
Carolina. It usually es 
tablishes itself upon brok 
en angular bits of rock, 
lying in sheltered creeks 
and inlets, where the vio 
lent action of the open sea is not felt. The presence of one of 
these little communities on a rock may first be detected by what 
seems like a delicate white film over the surfkce. This film is, 
however, broken up by a number of hard calcareous deposits in 
very regular form (Fig. 20), circular in outline, but divided by 
numerous partitions running from the outer wall to the centre of 
every such circle, where they unite at a little white spot formed by 
the mouth or oral opening. These circles represent, and indeed 
are themselves the distinct individuals (Fig. 17) composing the 
community, and they look Fig. 17. 

not unlike the star-shaped 
pits on a coral head, formed 
by Astraeans. Unlike the 
massive compact kinds of 
coral, however, the indi 
viduals multiply by bud 
ding from the base chiefly, 
never rising one above the 
other, but spreading over 
the surface on which they 
have established them 
selves, a few additional individuals arising between the older 
ones. In consequence of this mode of growth, such a commu- 

Fig. 16. Astranpria colony 5 natural size. 

Fig. 17. Magnified individuals of an Astrangia community in different stages of expansion. 
3 





18 MARINE ANIMALS OF MASSACHUSETTS BAY. 

nity, when it has attained any size, forms a little white mound on 
the rock, higher in the centre, where the older members have 
attained their whole height and solidity, and thinning out toward 
the margin, where the younger ones may be just beginning life, 
and hardly rise above the surface of the rock. These communi 
ties .rarely grow to be more than two or three inches in diameter, 
and about quarter of an inch in height at the centre where the 
individuals have reached their maximum size. When the ani 
mals are fully expanded (Fig. 18), with all their tentacles spread, 
i<r 18> the surface of every such mound 

becomes covered with downy 
white fringes, and what seemed 
before a hard, calcareous mass 
upon the rock, changes to a soft 
fleecy tuft, waving gently to and 
fro in the water. The tentacles 
are thickly covered with small wart-like appendages, which, on 
examination, prove to be clusters of lasso-cells, the terminal 
cluster of the tentacle being quite prominent. These lasso-cells 
are very formidable weapons, judging both from their appearance 
when magnified (Fig. 19), and from the terrible effect of their 
bristling lash upon any small crustacean, or worm, that 
may be so unfortunate as to come within its reach. 

The description of the internal arrangement of parts 
in the Actinia applies in every particular to these corals, 
with the exception of the hard deposit in the lower part 
of the body. As in all the Polyps, radiating partitions 
divide the main cavity of the body into distinct separate 
chambers, and the tentacles increasing by multiples of 
six, numbering six in, the first set, six in the second, and 
twelve in the third, are hollow, and open into the cham 
bers. But the feature which distinguishes them from 
the soft Actinia?, and unites them with the corals, re 
quires a somewhat more accurate description. In each 
individual, a hard deposit is formed (Fig. 20), beginning 
at the base of every chamber, and rising from its floor to about 

Fig. 18. Single individual of Astrangia, fully expanded. 
Fig. 19. Magnified lasso-cell of Astrangia. 



HALCYOXOIDS. 



19 



one fifth the height of the animal at its greatest extension. This 
lime deposit does not, however, fill Fig 20 

the chamber for its whole width, but 
rises as a thin wall in its centre. (See 
Figs. 16, IT.) Thus between all the 
soft partitions, in the middle of the 
chambers which separate them, low 
lime-stone walls are gradually built 
up, uniting in a solid column in the 
centre. These walls run parallel 
with the soft partitions, although 
they do not rise to the same height, 

and they form the radiating lines like stiff lamellae, so conspicu 
ous when all the soft parts of the body are drawn in. The mouth 
of the Astrangia is oval, and the partitions spread in a fan-shaped 
way, being somewhat shorter at one side of the animal than on 
the other. The partitions extend beyond the solid wall which 
unites them at the periphery, in consequence of which, this wall 
is marked by faint vertical ribs. 




HALCYONOIDS.X 



Haley Onium. (Halcyonium 







Libr&ry* 




WE come now to the Halcyonoids, represented in our waters 
by the Halcyonium (Fig. 22). In the Halcyonoids, the 
highest group of Polyps, the tentacles reach their greatest 
limitation, which, as above mentioned, is found to be a mark 
of superiority, and, connected with other struc- Fig. 21. 

tural features, places them at the head of their 
class. The number of tentacles throughout this 
group is always eight. They are very compli 
cated (Fig. 21), in comparison with the tenta 
cles of the lower orders, being deeply lobed, 




Fig. 20. Limestone parts of an individual of Astrangia; magnified. 
Fig. 21. Single individual of Halcyonium seen from above; magnified. 




20 MARINE ANIMALS OF MASSACHUSETTS BAY. 

and fringed around the margin. Our Halcyonium communities 
r . 22 (Fig. 22) iisually live in deep water, 

attached to dead shells, though they 
may occasionally be found growing at 
low-water mark, but this is very rare. 
They have received a rather lugubri 
ous name from the fishermen, who call 
them " dead-men s fingers," and in 
deed, when the animals are contract 
ed, such a community, with its short 
branches attached to the main stock, 
looks not unlike the stump of a hand, 
with short, fat fingers. In such a con 
dition they are very ugly, the whole 
mass being somewhat gelatinous in tex 
ture, and a dull, yellowish pink in color. 
But when the animals, which are capable of great extension, are 
fully spread, as in Fig. 22, such a polyp-stock has a mossy, tufted 
look, and is by no means an unsightly object. When the individ 
uals are entirely expanded, as in Fig. 23, they be 
come quite transparent, and their internal structure 
can readily be seen through the walls of the body ; 
we can then easily distinguish the digestive cavity, 
supported for its whole length by the eight radiating 
partitions, as well as the great size of the main diges 
tive cavity surrounding it. Notwithstanding the re 
markable power of contraction and dilatation in 
the animals themselves, the tentacles are but slight 
ly contractile. This kind of community increases 
altogether by budding, the individual polyps remaining more or 
less united, the tissues of the individuals becoming thicker by 
the deposition of lime nodules, and thus forming a massive 
semi-cartilaginous pulp, uniting the whole community. In the 
neighborhood of Provincetown they are very plentiful, and are 
found all along the shores of our Bay in deep water. 

Fig. 22. Ilalcyonium community, natural size. 

Fig. 23. Individual of Ilalcyonium fully expanded j magnified. 




GENERAL SKETCH OF ACALEPHS. 21 



GENERAL SKETCH OF ACALEPHS. 

IN the whole history of metamorphosis, that wonderful chapter 
in the life of animals, there is nothing more strange or more in 
teresting than the transformations of the Acalephs. First, as 
little floating planulae or transparent spheres, covered with fine 
vibratile cilia, by means of which they move with great rapidity, 
then as communities fixed to the ground and increasing by bud 
ding like the corals, or multiplying by self-division, and later as 
free-swimming Jelly-fishes, many of them pass through phases 
which have long baffled the investigations of naturalists, and have 
only recently been understood in their true connection. Great 
progress has, however, been made during this century in our 
knowledge of this class. Thanks to the investigations of Sars, Du- 
jardin, Steenstrup, Van Beneden, and many others, we now have 
the key to their true relations, and transient phases of growth, 
long believed to be the adult condition of distinct animals, are 
now recognized as parts in a cycle of development belonging to 
one and the same life. As the class now stands, it includes three 
orders, highest among which are the CTENOPHOILE, so called on 
account of their locomotive organs, consisting of minute flappers 
arranged in vertical comb-like rows ; next to these are the Dis 
COPHOR.E, with their large gelatinous umbrella-like disks, com 
monly called Jelly-fishes, Sun-fishes, or Sea-blubbers, and below 
these come the HYDROIDS, embracing the most minute and most 
diversified of all these animals. 

These orders are distinguished not only by their striking ex 
ternal differences, but by their mode of development also. The 
Ctenophoras grow from eggs by a direct continuous process of 
development, without undergoing any striking metamorphosis ; 
the Discophorae, with some few exceptions, in which they develop 
like the Ctenophorae from eggs, begin life as a Hydra-like ani 
mal, the subsequent self-division of which gives rise, by a singular 
process, presently to be described, to a number of distinct Jelly- 
fishes ; the Hydroids include all those Acalephs which either 
pass the earlier stages of their existence as little shrub-like com- 



22 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 24. 



munities, or remain in that condition through life. These Hy 
droid stocks, as they are sometimes called, give rise to buds ; 
these buds are transformed into Jelly-fishes, which in some in 
stances break off when mature and swim away as free animals, 
while in others they remain permanent members of the Hydroid 
stock, never assuming a free mode of life. All these buds when 
mature, whether free or fixed, lay eggs in their turn, from which 
a fresh stock arises to renew this singular cycle of growth, known 
among naturalists as " alternate generations." 

The Hydroids are not all attached to the ground, some 
like the Physalia (Portuguese man-of-war), or the Nanomia, that 
pretty floating Hydroid of our own waters, move about with as 
much freedom as if they enjoyed an individual independent ex 
istence. As all these orders have their representatives on our 
coast, to be described hereafter in detail, we need only allude 
here to their characteristic features. But we must not leave un 
noticed one very remarkable Hydroid Acaleph (Fig. 24), not 
found in our waters, and resembling the 
Polyps so much, that it has long been asso 
ciated with them. The Millepore is a coral, 
and was therefore the more easily confounded 
with the Polyps, so large a proportion of 
which build coral stocks ; but a more mi 
nute investigation of its structure (Figs. 25, 
26) has recently shown that it belongs with 
the Acalephs.* This discovery is the more 
important, not only as explaining the true po 
sition of this animal in the Animal Kingdom, 
but as proving also the presence of Acalephs 
in the earliest periods of creation, since it re 
fers a large number of fossil corals, whose 
affinities with the millepores are well under 
stood, to that class, instead of to the class of 
Polyps with which they had hitherto been associated. But for 
this we should have no positive evidence of the existence of 

Fig. 24. Branch of Millepora alcicornis; natural size. (Agassiz.") 

Fig. 25. Animals of M. alcicornis expanded; magnified, aaa small Hydroid, b larger Hydroid, 
I tentacles, m mouth. (Agassiz.) 

* See " Methods of Study," by Prof. Agassiz. 




Fig. 25. 





GENERAL SKETCH OF ACALEPHS. 23 

Acalephs in early geological periods, the gelatinous texture 

of the ordinary Jelly-fishes making their preserva- Kg. 26. 

tion almost impossible. It is not strange that the 

true nature of this animal should have remained 

so long unexplained ; for it is only by the soft 

parts of the body, not of course preserved in the 

fossil condition, that their relations to the Acalephs 

may be detected ; and they are so shy of approach, 

drawing their tentacles and the upper part of the 

body into their limestone frame if disturbed, that it is not 

easy to examine the living animal. 

The Millepore is very abundant on the Florida reefs. From the 
solid base of the coral stock arise broad ridges, branching more or 
less along the edges, the whole surface being covered by innu 
merable pores, from which the diminutive animals project when 
expanded. (Fig. 25.) The whole mass of the coral is porous, 
and the cavities occupied by the Hydras are sunk perpendicularly 
to the surface within the stock. Seen in a transverse cut these 
tubular cavities are divided at intervals by horizontal partitions 
(Fig. 26), extending straight across the cavity from wall to wall, 
and closing it up entirely, the animal occupying only the outer 
most open space, and building a new partition behind it as it 
rises in the process of growth. This structure is totally different 
from that of the Madrepores, Astrasans, Porites, and indeed, from 
all the polyp corals which, like all Polyps, have the vertical par 
titions running through the whole length of the body, and more 
or less open from top to bottom. 

The life of the Jelly-fishes, with the exception of the Mille- 
pores and the like, is short in comparison to that of other Radi 
ates. While Polyps live for many years, and Star-fishes and 
Sea-urchins require ten or fifteen years to attain their full size, 
the short existence of the Acaleph, with all its changes, is accom 
plished in one year. The breeding season being in the autumn, 
the egg grows into a Hydroid during the winter ; in the spring the 
Jelly-fish is freed from the Hydroid stock, or developed upon it as 
the case may be ; it attains its full size in the fall, lays its eggs 

Fiji. 26. Transverse section of a branch, showing pits, a a a a, of the large Ilydroids with the hori 
zontal floors, 



24 MARINE ANIMALS OF MASSACHUSETTS BAY. 

and dies, and the cycle is complete. The autumn storms make 
fearful havoc among them, swarms of them being killed by the fall 
rains, after which they may be found thrown up on the beaches 
in great numbers. When we consider the size of these Jelly- 
fishes, their rapidity of growth seems very remarkable. Our 
common Aurelia measures some twelve to eighteen inches in 
diameter when full grown, and yet in the winter it is a Hydra so 
small as almost to escape notice. Still more striking is the rapid 
increase of our Cyanea, that giant among Jelly-fishes, which, 
were it not for the soft, gelatinous consistency of its body, would 
be one of the most formidable among our marine animals. 

Before entering upon the descriptions of the special kinds of 
Jelly-fishes, we would remind our readers that the radiate plan of 
structure is reproduced in this class of animals as distinctly as in 
the Polyps, though under a different aspect. Here also we find 
that there is a central digestive cavity from which all the radiat 
ing cavities, whether simple or ramified, diverge toward the peri 
phery. It is true that the open chambers of the Polyps are here 
transformed into narrow tubes, by the thickening of the dividing 
partitions, or in other words, the open spaces of the Polyps cor 
respond to tubes in the Acalephs, while the partitions in the 
Polyps correspond to the thick masses of the body dividing the 
tubes in the Acalephs ; but the principle of radiation on which 
the whole branch of Radiates is constructed controls the organi 
zation of Acalephs no less than that of the other classes, so that 
a transverse section across any Polyp (Fig. 1), or across any 
Acaleph (Fig. 50), or across any Echinoderm (Fig. 140), shows 
their internal structure to be based upon a radiation of all parts 
from the centre to the periphery. 

That there may be no vagueness as to the terms used here 
after, we would add one word respecting the nomenclature of this 
class, whose aliases might baffle the sagacity of a police detective. 
The names Acalephs, Medusae, or the more common appellation 
of Jelly-fishes, cover the same ground, and are applied indiscrim 
inately to the animals they represent. The name Jelly-fish is an 
inappropriate one, though the gelatinous consistency of these 
animals is accurately enough expressed by it ; but they have no 
more structural relation to a fish than to a bird or an insect. 



GENERAL SKETCH OF ACALEPHS. 25 

They have, however, received this name before the structure of 
animals was imderstood, when all animals inhabiting the waters 
were indiscriminately called fishes, and it is now in such general 
use that it would be difficult to change it. The name Medusa is 
derived from their long tentacular appendages, sometimes wound 
up in a close coil, sometimes thrown out to a great distance, 
sometimes but half unfolded, and aptly enough compared to the 
snaky locks of Medusa. Their third and oldest appellation, that of 
Acalephs, alluding to their stinging or nettling property, and 
given to them and like animals by Aristotle, in the first instance, 
but afterwards applied by Cuvier in a more limited sense to 
Jelly-fishes, is the most generally accepted, and perhaps the 
most appropriate of all. 

The subject of nomenclature is not altogether so dry and 
arid as it seems to many who do not fully understand the signifi 
cance of scientific names. Not only do they often express with 
terse precision the character of the animal or plant they signify, 
but there is also no little sentiment concealed under these jaw- 
breaking appellations. As seafaring men call their vessels after 
friends or sweethearts, or commemorate in this way some impres 
sive event, or some object of their reverence, so have naturalists, 
under their fabrication of appropriate names, veiled many a grace 
ful allusion, either to the great leaders of our science, or to some 
more intimate personal affection. The Linncea borealis was well 
named after his famous master, by a disciple of the great Nor 
wegian naturalist ; G-oethea semper flor ens, the ever-blooming, is 
another tribute of the same kind, while the pretty, graceful little 
Lizzia, named by Forbes, is one instance among many of a more 
affectionate reference to nearer friends. The allusions of this 
kind are not always of so amiable a character, however, witness 
the " Buffonia," a low, noxious weed, growing in marshy places, 
and named by Linnaeus after Buffon, whom he bitterly hated. 
Indeed, there is a world of meaning hidden under our zoological 
and botanical nomenclature, known only to those who are inti 
mately acquainted with the annals of scientific life in its social as 
well as its professional aspect. 



26 MARINE ANIMALS OF MASSACHUSETTS BAY. 



CTENOPHOR^]. 

THE Ctenopliorse differ from other Jelly-fishes in their mode of 
locomotion. All the Discophorous Medusae, as well as Hydroids, 
move by a rhythmical rise and fall of the disk, contracting and 
expanding with alternations so regular, that it reminds one of the 
action of the lungs, and seems at first sight to be a kind of res 
piration in which water takes the place of air. The Greeks rec 
ognized this peculiar character in their name, for they called 
them Sea-lungs. Indeed, locomotion, respiration, and circulation 
are so intimately connected in all these lower animals, that what 
ever promotes one of these functions affects the other also, and 
though the immediate result of the contraction and expansion 
of the disk seems to be to impel them through the water, yet 
it is also connected with the introduction of water into the body, 
which there becomes assimilated with the food in the process of 
digestion, and is circulated throiighout all its parts by means of 
ramifying tubes. In the Ctenophoras there is no such regular 
expansion and contraction of the disk ; they are at once dis 
tinguished from the Discophorse by the presence of external 
locomotive appendages of a very peculiar character. They move 
by the rapid napping of countless little oars or paddles, arranged 
in vertical rows along the surface of the disk, acting indepen 
dently of each other ; one row, or even one paddle, moving singly, 
or all of them together, at the will of the animal ; thus ena 
bling it to accelerate or slacken its movements, to dart through 
the water rapidly, or to diminish its speed by partly furling its 
little sails, or, spreading them slightly, to poise itself with a faint, 
quivering movement that reminds one of the pause of the hum 
ming-bird in the air, something that is neither positive motion, 
nor actual rest.* 

These locomotive appendages are intimately connected with 
the circulating tubes, as we shall see when we examine the struc- 

* The flappers of one side are sometimes in full activity, while those of the other 
side are perfectly quiet or nearly so, thus producing rotatory movements in every 
direction. 



PLEUROBRACHIA. 27 

tural details of these animals, so that in them also breathing and 
moving are in direct relation to each other. To those unaccus 
tomed to the comparison of functions in animals, the use of the 
word breathing, as applied to the introduction of water into the 
body, may seem inappropriate, but it is by the absorption of 
aerated water that these lower animals receive that amount of 
oxygen into the system, as necessary to the maintenance of life in 
them, as a greater supply is to the higher animals. The name 
of Ctenophoras or comb-bearers, is derived from these rows of 
tiny paddles which have been called combs by some naturalists, 
because they are set upon horizontal bands of muscles, see Fig. 
29, reminding one of the base of a comb, while the fringes are 
compared to its teeth. These flappers add greatly to the beauty 
of these animals, for a variety of brilliant hues is produced along 
each row by the decomposition of the rays of light upon them 
when in motion. They give off all the prismatic colors, and as 
the combs are exceedingly small, so that at first sight one 
hardly distinguishes them from the disk itself, the exquisite play 
of color, rippling in regular lines over the surface of the animal, 
seems at first to have no external cause. 

Pleurobrachia. (Pleurobrachia rJiododactyla AG.) 

Among the most graceful and attractive of these animals are 
the Pleurobrachia (Fig. 29), and, though not first in order, we 
will give it the precedence in our description, because it will 
serve to illustrate some features of the other two groups. The 
body of the Pleurobrachia consists of a transparent sphere, vary 
ing, however, from the perfect sphere in being somewhat ob 
long, and also by a slight compression on two opposite sides 
(Figs. 27 and 28), so as to render its horizontal diameter longer 
in one direction than in the other (Fig. 30). 
This divergence from the globular form, so slight 
in Pleurobrachia as to be hardly perceptible to 
the casual observer, establishing two diameters of 
different lengths at right angles with each other, 
is equally true of the other genera. It is inter 
esting and important, as showing the tendency in 

Fig. 27. Pleurobrachia seen at right angles to the plane In which the tentacles are placed. (Ayassiz.) 





28 MARINE ANIMALS OF MASSACHUSETTS BAY. 

this highest group of Acalephs to assume a bi 
lateral character. This bilaterality becomes still 
more marked in the highest class of Radiates, the 
Echinoderms. Such structural tendencies in the 
\8 |H|5fei Jjl lower animals, hinting at laws to be more fully 
developed in the higher forms, are always signifi 
cant, as showing the intimate relation between all 
parts of the plan of creation. This inequality of 
the diameters is connected with the disposition of parts in the 
whole structure, the locomotive fringes and the vertical tubes 
connected with them being arranged in sets of four on either side 
of a plane passing through the longer diameter, showing ,thus a 
tendency toward the establishment of a right and left side of the 
body, instead of the perfectly equal disposition of parts around a 
common centre, as in the lower Radiates. 

The Pleurobrachia are so transparent, that, with some prepara 
tory explanation of their structure, the most unscientific observer 
may trace the relation of parts in them. At one end of the sphere 
is the transverse split (Fig. 27), that serves them as a mouth ; at 
the opposite pole is a small circumscribed area, in the centre 
of which is a dark eye-speck. The eight rows of locomotive 
fringes run from pole to pole, dividing the whole surface of the 
body like the ribs on a melon. (Figs. 27, 28.) Hanging from 
either side of the body, a little above the area in which the eye- 
speck is placed, are two most extraordinary appendages in the 
shape of long tentacles, possessing such wonderful power of ex 
tension and contraction that, while at one moment they may be 
knotted into a little compact mass no bigger than a pin s head, 
drawn up close against the side of the body, or hidden within it, 
the next instant they may be floating behind it in various posi 
tions to a distance of half a yard and more, putting out at the 
same time soft plumy fringes (Fig. 29) along one side, like the 
beard of a feather. One who has never seen these animals may 
well be pardoned for doubting even the most literal and matter- 
of-fact account of these singular tentacles. There is no variety 
of curve or spiral that does not seem to be represented in their 
evolutions. Sometimes they unfold gradually, creeping out softly 

Fig. 23. Pleurobrachia seen in plane of tentacles. (Agassiz.) 



PLEUKOBRACHIA. 



29 



Fig. 29. 




and slowly from a state of contraction, or again the little ball, 
hardly perceptible against the side of the body, drops suddenly 
to the bottom of 
the tank in which 
the animal is float 
ing, and one thinks 
for a moment, so 
slight is the thread 
like attachment, 
that it has actual 
ly fallen from the 
body ; but watch a 
little longer, and 
all the filaments 
spread out along 
the side of the 
thread, it expands 
to its full length 
and breadth, and resumes all its graceful evolutions. 

One word of the internal structure of these animals, to explain 
its relation to the external appendages. The mouth opens into a 
wide digestive cavity (Figs. 27, 28), enclosed between two verti 
cal tubes. Toward the opposite end of the body these tubes 
terminate or unite in a single funnel-like canal, which is a reser 
voir as it were for the circulating fluid poured into it through an 
opening in the bottom of the digestive cavity. The food in the 
digestive cavity becomes liquefied by mingling with the water 
entering with it at the mouth, and, thus prepared, it passes into 
this canal, from which, as we shall presently see, all the circulat 
ing tubes ramifying throughout the body are fed. Two of these 
circulating tubes, or, as they are called from the nature of the 
liquid they contain, chymiferous tubes, are very large, starting 
horizontally and at right angles with the digestive cavity from 
the point of junction between the vertical tubes (Fig. 30) and 
the canal. Presently they give off two branches, these again 
ramifying in two directions as they approach the periphery, so 
that each one of the first main tubes has multiplied to four, 



Fig. 29. Natural attitude of Pleurobrachia when in motion. 




30 MARINE ANIMALS OF MASSACHUSETTS BAY. 

before its ramifications reach the surface, thus making in all 

eight radiating tubes. So far, these 
eight tubes are horizontal, all diverging 
on the same level ; but as they reach 
the periphery each one gives rise to 
a vertical tube, running along the sur 
face of the body from pole to pole, just 
within the rows of locomotive fringes 
on the outer surface, and immediately 
connected with them (Figs. 27, 28). As 
in all the Ctenophorae, these fringes keep 

up a constant play of color by their rapid vibrations. In Pleuro- 
brachia the prevailing tint is a yellowish pink, though it varies to 
green, red, and purple, with the changing motions of the animal. 
We have seen that the vertical tubes between which the digestive 
cavity is enclosed, start like the cavity itself from that pole of the 
body where the mouth is placed, and that, as they approach the 
opposite pole, at a distance from the mouth of about two thirds 
the whole length of the body, they unite in the canal, which then 
extends to the other pole where the eye-speck is placed. As it is 
just at this point of juncture between the tubes and the canal 
that the two main horizontal tubes arise from which all the 
others branch on the same plane (Figs. 27, 28), it follows 
that they reach the periphery, not on a level with the pole op 
posite the mouth, but removed from it by about one third the 
height of the body. In consequence of this the eight vertical 
tubes arising from the horizontal ones, in order to run the entire 
length of the body from pole to pole, extend in opposite direc 
tions, sending a branch to each pole, though the branch running 
toward the mouth is of course the longer of the two. The tenta 
cles have their roots in two sacs within the body, placed at right 
angles with the split of the mouth. (Figs. 27, 30.) They open 
at the surface on the opposite side from the mouth, though not 
immediately within the area at which the eye-speck is placed, 
but somewhat above it, and at a little distance on either side of it. 
The tentacles may be drawn completely within these sacs, or be 
extended outside, as we have seen, to a greater or less degree, and 
in every variety of curve or spiral. 

Fig. 30. Pleurobrachia seen from the extremity opposite the mouth. 



BOLINA. 



31 




Bolina. {Bolina alata Ac.) 

THE Bolina (Fig 32), like the Pleurobrachia, is slightly oval in 
form, with a longitudinal split at one end of the body, forming a 
month which opens into a capacious sac or digestive cavity. 
But it differs from the Pleurobrachia in having the oral end of 
the body split into two larger lobes (Fig. 31), hanging down 
from the mouth. These lobes may gape rifr 31 

widely, or they may close completely 
over the mouth so as to hide it from 
view, and their different aspects under 
various degrees of expansion or contrac 
tion account for the discrepancies in the 
description of these animals. We have 
seen that the Pleurobrachia moves 
with the mouth upward ; but the Bo 
lina, on the contrary, usually carries 
the mouth downward, though it occasionally reverses its position, 
and in this attitude, with the lobes spread open, it is exceedingly 
graceful in form, and looks like a white flower with the crown 
fully expanded. These broad lobes are balanced on the other 
sides of the body by four smaller appendages, divided in pairs, 
two 011 each side (Fig. 32), called auricles. These so-called 
aiiricles are in fact organs of the same kind 
as the larger lobes, though less developed. 
The rows of locomotive flappers on the Bo 
lina differ in length from each other (Fig. 
31), instead of being equal, as in the Pleu 
robrachia. The four longest ones are op 
posite each other on those sides of the body 
where the larger lobes are developed, the 
four short ones being in pairs on the sides 
where the auricles are placed. At first sight 
they all seem to terminate at the margin of the body, but a closer 

Fig. 31. Bolina seen from the broad side ; o eye-speck, m mouth, r auricles, v digestive cavity, g h 
short rows of flappers, af long rows of flappers, nxtz tubes winding in the larger lobes; about half 
natural size. (Ayassiz.) 

Fig. 32. Bolina seen from the narrow side ; c h short rows of flappers, a b long rows of flappers ; 
other letters as in Fig. 31. (Acjassiz.) 



Fig. 32. 




32 MARINE ANIMALS OF MASSACHUSETTS BAY. 

examination shows that the circulating tubes connected with the 
longer row extend into the lobes, where they wind about in a 
variety of complicated involutions. (Fig. 32.) The movements 
of the Bolina are more sluggish than those of the Pleurobrachia, 
and the long tentacles, so graceful an ornament to the latter, are 
wanting in the former. With these exceptions the description 
given above of the Pleurobrachia will serve equally well for the 
Bolina. The structure is the same in all essential points, though 
it differs in the size and proportion of certain external features, 
and its play of color is less brilliant than that of the Pleuro 
brachia. The Bolina, with its slow, undulating motion, its broad 
lobes sometimes spreading widely, at other times folded over the 
mouth, its delicacy of tint and texture, and its rows of vibrating 
fringes along the surface, is nevertheless a very beautiful object, 
and well rewards the extreme care without which it dies at once 
in confinement. 

Idyitt. (Idyia roseola AG.) 

The lowest genus of Ctenophorse found on our coast, the Idyia 
(Fig. 33) , has neither the tentacles of the Pleurobrachia, nor the 
lobes of the Bolina. It is a simple ovate sphere, the interior of 
which is almost entirely occupied by an immense digestive cavity. 
It would seem that the reception and digestion of food is intended 
33 to be the almost exclusive function of this 

animal, for it has a mouth whose ample di 
mensions correspond with its capacious stom 
ach. Instead of the longitudinal split serving 
as a mouth, in the Bolina and Pleurobrachia, 
one end of the body in the Idyia is completely 
open (Fig. 33), so that occasionally some un 
suspicious victim of smaller diameter than 
itself may be seen to swim into this wide por 
tal, when suddenly the door closes behind him 
with a quick contraction, and he finds himself a prisoner. The 
Idyia does not always obtain its food after this indolent fashion 

Fig. 33 Idyia roseola seen from the broad side, half natural size ; a anal opening, b lateral tube, c 
circular tube, d efg h rows of locomotive flappers. ( Ayassiz.) 




IDYIA. 33 

however, for it often attacks a Bolina or Pleurobrachia as large 
or even larger than itself, when it extends its mouth to the ut 
most, slowly overlapping the prey it is trying to swallow by fre 
quent and repeated contractions, and even cutting off by the 
same process such portions as cannot be forced into the digestive 
cavity. 

The general internal structure of the Idyia corresponds with 
that of the Bolina and Pleurobrachia ; it has the same tubes 
branching horizontally from the main cavity, then ramifying as 
they approach the periphery till they are multiplied to eight in 
all, each of which gives off one of the vertical tubes connected 
with the eight rows of locomotive flappers. Opposite the mouth 
is the eye-speck, placed as in the two other genera, at the centre 
of a small circumscribed area, which in the Idyia is surrounded 
by delicate fringes, forming a rosette at this end of the body. 
These animals are exceedingly brilliant in color ; bright pink is 
their prevailing hue, though pink, red, yellow, orange, green, 
and purple, sometimes chase each other in quick succession along 
their locomotive fringes. At certain seasons, when most numer 
ous, they even give a rosy tinge to patches on the surface of the 
sea. Their color is brightest and deepest before the spawning 
season, but as this advances, and the ovaries and spermaries are 
emptied, they grow paler, retaining at last only a faint pink tint. 
They appear early in July, rapidly attain their maximum size, 
and are most numerous during the first half of August. Toward 
the end of August they spawn, and the adults are usually de 
stroyed by the early September storms, the young disappearing 
at the same time, not to be seen again till the next summer. It 
is an interesting question, not yet solved, to know what becomes 
of the summer s brood in the following winter. They probably 
sink into deep waters during this intervening period. The Idyia, 
like the Pleurobrachia, moves with the mouth upward, but in 
clined slightly forward also, so as to give an oblique direction to 
the axis of the body.* 

* Until this summer only the three genera of Ctenophorae above mentioned were 

supposed to exist along our coast, but during the present season I have had the good 

fortune to find two additional ones. One of them, the Lesueuria, resembles a Bolina 

with the long lobes so cut off, that they have a very stunted appearance in compari- 

5 



34 MARINE ANIMALS OF MASSACHUSETTS BAY. 



EMBRYOLOGY OF CTENOPHORAE. 

ALL the Ctenophorae are reproduced from eggs, these eggs 
being so transparent that one may follow with comparative ease 
the changes undergone by the young while still within the egg 
envelope. Unfortunately, however, they are so delicate that it is 
impossible to keep them alive for any length of time, even by 
supplying them constantly with fresh sea-water, and keeping 
them continually in motion, both of which are essential conditions 
to their existence. It is therefore only from eggs accidentally 
fished up at different stages of growth that we may hope to ascer 
tain any facts respecting the sequence of their development. 
When hatched, the little Ctenophore is already quite advanced. 
It is small when compared with the size of the egg envelope, and 
long before it is set free, it swims about with great velocity with 
in the walls of its diminutive prison (Fig. 35). The importance 
of studying the young stages of animals can hardly find a better 
illustration than among the Ctenophora3. Before their extraor 
dinary embryonic changes were understood, many of the younger 
forms had found their way into our scientific annals as distinct 
animals, and our nomenclature thus became burdened with 
long lists of names which will disappear as our knowledge ad 
vances. 

The great size of their locomotive flappers in proportion to the 
rest of the body, is characteristic of the young Ctenophorae. 
They seem like large paddles on the sides of these tiny trans 
parent spheres, and, owing to their great power as compared with 
those of the adult, the young move with extraordinary rapidity. 
The Pleurobrachia alone retains its quickness of motion in after 
life, and although its long graceful streamers appear only as short 
stumpy tentacles in the young (Fig. 34), yet its active little body 
would be more easily recognized in the earlier stages of growth 

son with those of the Bolina. The other, the Mertensia, is closely allied to Pleuro 
brachia ; it is exceedingly flattened and pear-shaped. This species was discovered 
long ago by Fabricius, but had escaped thus far the attention of other naturalists. 
(A. Agassiz.) 



EMBRYOLOGY OF CTENOPHOR^E. 



35 



than that of the other Ctenophorae. Figs. 34, 35, and 36 show 
the Pleurobrachia at various stages of growth ; Fig. 34, with its 
thick stunted tentacles and short rows of flappers, is the youngest; 
the flappers themselves are rather long at this age, looking more 
like stiff hairs than like the minute fringes of the adult. In Fig. 

Fig. 34. Fig. 35. 





35 the tentacles are already considerably longer and more deli 
cate ; in Fig. 36 the vertical tubes are already completed, while 
Figs. 27-29 present it in its adult condition. 

The Idyia differs greatly in appearance at different periods of 

Fig. 36 Fig. 37. 





its development, and, indeed, no one would suspect, without some 
previous knowledge of its transformations, that the young Idyia, 

Fig. 34. Young Pleurobrachia still in the egg ; t tentacles, e eye-speck, c c rows of locomotive flap 
pers, d digestive cavity; greatly magnified. 

Fig. 36. Young Pleurobrachia swimming about in the egg just before hatching ; magnified. 

Fig. 36. Young Pleurobrachia resembling somewhat the adult ; /funnel leading to anal opening, I 
lateral tubes, c c c c 1 rows of locomotive flappers; magnified. 

Fig. 37. Young Idyia, greatly magnified ; lettering as in Fig. 36 ; d digestive cavity. 



36 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



with its rapid gyrations, its short ambnlacral tubes, like immense 
pouches (Fig. 37), its large pigment spots scattered over the sur 
face (Fig. 38), was an earlier stage of the rosy-hued Idyia, which 
glides through the water with a scarcely perceptible motion. 

Fig. 38. Fig. 39. 





Fig. 40. 



Figs. 37-40 represent the various stages of its growth. It will 
be seen how very short are the locomotive fringes (Fig. 39) in 
comparison with those of the full-grown ones (Fig. 33). It is 

only in the adult Idyia that these rows 
attain their full height, and the tubes, 
ramifying throughout the body (Fig. 
40), are completed. 

The Bolina, in its early condition, 
recalls the young Pleurobrachia. 
At this period it has the same rapid 
motion, and when somewhat more 
advanced, long tentacles, resembling 
those of the Pleurobrachia, make 
their appearance (Fig. 41) ; it is only 
at a later period that the tentacles 
become contracted, while the large 
lobes (Fig. 42), so characteristic of 

Bolina, are formed by the elongation of the oral end of the 
body, the auricles becoming more conspicuous at the same 

Fig. 38. Young Idyia seen from the anal extremity, magnified 5 a anal opening, other letters as in 
Fig. 36. 

Fig. 39. Idyia somewhat older than Fig. 37, lettering as before ; magnified. 

Fig. 40. Young Idyia in which the ambulacral tubes begin to ramify ; magnified, letters as before. 




DISCOPHOILE. 37 

time (Fig. 43). A little later the lobes enlarge, the movements 
become more lazy ; it assumes both in form and habits the char 
acter of the adult Bolina. 

The series of changes through which the Ctenophoras pass 

Fig. 41. Fig. 42. Fig. 43. 








are as remarkable as any we shall have occasion to describe, 
though not accompanied with such absolutely different con 
ditions of existence. The comparison of the earlier stages of 
life in these animals with their adult condition is important, 
not only with reference to their mode of development, but also 
because it gives us some insight into the relative standing of the 
different groups, since it shows us that certain features, perma 
nent in the lower groups, are transient in the higher ones. A 
striking instance of this occurs in the fact mentioned above, that 
though the long tentacles so characteristic of the adult Pleuro- 
brachia exist in the young Bolina, they yield in importance at 
a later period to the lobes which eventually become the pre 
dominant and characteristic feature of the latter. 



DISCOPHOR^E. 

THE disk of the Discophorse is by no means so delicate as that 
of the other Jelly-fishes. It seems indeed quite solid, and some 
what like cartilage to the touch, and yet so large a part of its 
bulk consists of water, that a Cyanea, weighing when alive about 
thirty-four pounds, being left to dry in the sun for some days, was 

Fig. 41. Young Bolina in stage resembling Pleurobrachia ; greatly magnified. 

Fig. 42. Young Bolina seen from the broad side, with rudimentary auricles and lobes; magnified. 

Fig. 43. The same as Fig. 42, seen from the narrow side. 



38 MARINE ANIMALS OF MASSACHUSETTS BAY. 

found to have lost about -f^j of its original weight, only the 
merest film remaining on the paper upon which it had been laid. 
The prominence of the disk in this group of Jelly-fishes is well 
characterized by their German name, " Scheiben quallen," viz. 
disk-medusae. We shall see hereafter that the disk, so large and 
seemingly solid in the Discophorae, thins out in many of the other 
Jelly-fishes, and becomes exceedingly concave. This is especially 
the case in many of the Hydroid Medusae, where it assumes a 
bell-shaped form, and is constantly spoken of as the bell. It 
should be remembered, however, in reading descriptions of these 
animals, that the so-called bell is only a modified disk, and per 
fectly homologous with that organ in the Discophorae. 

The Discophorous Medusae are distinguished from all others by 
the peculiar nature of the reproductive organs. They are con 
tained in pouches (Fig. 50, 0,0,0,0), the contents of which are 
first discharged into the main cavity, and then pass out through 
the mouth. Pillars support the four angles of the digestive 
cavity, thus separating the lower from the upper floor of the disk, 
while the chymiferous tubes (Fig. 50) branch and run into 
each other near the periphery, forming a more or less compli 
cated anastomosing network, instead of a simple circular tube, as 
is the case with the Hydroid Medusae. (Fig. 74.) 

Cyanea. (Cyanea arctica PER. et LES.) 

In our descriptions of the Discophorae, we may give the pre 
cedence to the Cyanea on account of its size. This giant among 
Jelly-fishes is represented in Fig. 44. It is much to be regretted 
that these animals, when they are not so small as to escape atten 
tion altogether, are usually seen out of their native element, 
thrown dead or dying on the shore, a mass of decaying gelatinous 
matter. All persons who have lived near the sea are familiar 
with the so-called Sea-blubbers, sometimes strewing the sandy 
beaches after the autumn storms in such numbers that it is diffi 
cult to avoid them in walking or driving. In such a condition 
the Cyanea is far from being an attractive object ; to form an 
idea of his true appearance, one must meet him as he swims 
along at midday, rather lazily withal, his huge semi-transparent 



CYANEA. 39 

disk, with its flexible lobed margin, glittering in the sun, and his 
tentacles floating to a distance of many yards behind him. En 
countering one of those huge Jelly-fishes, when out in a row- 
boat one day, we attempted to make a rough measurement of his 
dimensions upon the spot. He was lying quietly near the sur 
face, and did not seem in the least disturbed by the proceeding, 
but allowed the oar, eight feet in length, to be laid across the 
disk, which proved to be about seven feet in diameter. Backing 
the boat slowly along the line of the tentacles, which were float 
ing at their utmost extension behind him, we then measured 
these in the same manner, and found them to be rather more 
than fourteen times the length of the oar, thus covering a space 
of some hundred and twelve feet. This sounds so marvellous 
that it may be taken as an exaggeration ; but though such an 
estimate could not of course be absolutely accurate, yet the facts 
are rather understated than overstated in the dimensions here 
given. And, indeed, the observation was more careful and pre 
cise than the circumstances would lead one to suppose, for the 
creature lay as quietly, while his measure was taken, as if he had 
intended to give every facility for the operation. This specimen 
was, however, of unusual size ; they more commonly measure 
from three to five feet across the disk, while the tentacles may 
be thirty or forty feet long. The tentacles are exceedingly 
numerous (see Fig. 44), arising in eight distinct bunches, from 
the margin of the disk, and hanging down in a complete laby 
rinth. 

These animals are not so harmless as it would seem, from 
their soft, gelatinous consistency ; it is no pleasant thing when 
swimming or bathing to "become entangled in this forest of fine 
feelers, for they have a stinging property like nettles, and may 
render a person almost insensible, partly from pain, and partly 
from a numbness produced by their contact, before he is able to 
free himself from the network in which he is caught. The 
weapons by which they produce these results seem so insignifi 
cant, that one cannot but wonder at their power. The tentacles 
are covered by minute cells, lasso-cells as they are called, (simi 
lar to those of Astrangia, Fig. 19,) each one of which contains 
a whip finer than the finest thread, coiled in a spiral within it. 




Fig. 44. Cyanea arctica ; greatly reduced in size. 



CYANEA. 



41 



These myriad whips can be thrown out at the will of the animal, 
and really form an efficient galvanic battery. Behind the veil 
of tentacles, and partly hidden by it, four curtains, with lobed or 
ruffled margins, dimly seen in Fig. 44, hang down from the un 
der surface of the disk. The ovaries are formed by four pendent 
pouches, placed near the sides of the mouth, and attached to four 
cavities within the disk. Around the circumference of the disk 
are eight eye-specks, each formed by a small tube protected un 
der a little lappet or hood rising from the upper surface of the 
disk. The prevailing color of this huge Jelly-fish is a dark 
brownish-red, with a light, milk-white margin, tinged with blue, 
the tentacles and other pendent appendages having a some 
what different hue from the disk. The ovaries are flesh-col 
ored, the curtain formed by the expansion of the lobes of the 
mouth is dark brown, while the tentacles are of different colors, 
some being yellow, others purple, and others reddish brown or 
pink. 

Strange to say, this gigantic Discophore is produced by a Hy- 
droid measuring not more than half an inch in height when full 
grown ; could we follow the history of any egg laid by one of 
these Discophorse in the autumn, which has indeed been par- 



Fig. 45. 





Fig. 46 




tially done, we should see that, like any other planula, the young 
hatched from the egg is at first spherical, but presently becomes 
pear-shaped, and attaches itself to the ground. From the upper 



Fig. 45. Scyphistoma of a Discophore ; Aurelia flavidula. (Agassiz.) 
Fig. 46. Scyphistoma, older than Fig. 45. (Agassiz.) 
Fig. 47. Strobila of a Discophore ; Aurelia flavidula. (Agassiz.) 
6 



42 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



end tentacles project (see Fig. 45), growing more numerous, as 
in Fig. 46, though they never exceed sixteen in number. As it 
increases in height constrictions take place at different distances 
along its length, every such constriction being lobed around its 
margin, till at last it looks like a pile of scalloped saucers or 
disks strung together (see Fig. 47). The topmost of these disks 
Fig. 48. falls off and dies ; but all the others separate 

by the deepening of the constrictions, and 
swim off as little free disks (Fig. 48), which 
eventually grow into the enormous Jelly-fish 
described above. These three phases of growth, 
before the relation between them was under 
stood, have been mistaken for distinct animals, 
and described as such under the names of Scyphistoma, Strobila, 
and Ephyra. 




Fig. 49. 



Aurelia. (Aurelia flavidula PER. et LES.) 

Another large Discophore, though by no means to be compared 
to the Cyanea in size, is our common Aurelia (Figs. 49, 50). 
Its bluish- white disk measures from twelve to fifteen inches in 
diameter, but its dimensions are not increased by the tentacles, 
which have no great power of contraction and expansion, and 
form a short fringe around its margin, widening and narrowing 

slightly as the tentacles 
are stretched or drawn 
in. It is quite trans 
parent, as may be seen 
in Fig 49, where all the 
fine ramifications of the 
chymiferous tubes, as 
well as the ovaries, are 
seen through the vault of the disk. Fig. 50 represents the upper 
surface, with the ovaries around the mouth, occupying the same 
position as those of the Cyanea, though they differ from the latter 
in their greater rigidity, and do not hang down in the form of 




Fig. 48. Ephyra of a Discophore ; Aurelia flavidula. (Ayassiz.) 
Fig. 49. Aurelia seen in profile, reduced. (Ayassiz.) 



AURELIA. 



43 



pouches. The males and females in this kind of Jelly-fish may 
be distinguished by the difference of color in the reproductive 
organs, which are rose-colored in the males, and of a dull yellow 
in the females. The process of development is exactly the same 
in the Aurelia as in the Cyanea, though there is a very slight 
difference, in their respective Hydroids. They are, however, so 
much alike, that one is here made to serve for both, the above 
figures being taken from the Hydroid of the Aurelia. It is 
curious, that while, as in the case of the Aurelia and Cyanea, 
very dissimilar Jelly-fishes may arise from almost identical Hy- 

Fig. 50. 




droids, we have the reverse of the proposition, in the fact that 
Hydroids of an entirely distinct character may produce similar 
Jelly-fishes. 

The embryos or little planula3, hatched from the Cyanea and 
Aurelia in the fall, seem to be gregarious in their mode of life, 
swimming about together in great numbers till they find a suit 
able point of attachment, and assume their fixed Hydroid exist 
ence. The Cyanea3, however, when adult, are usually found 
singly, while the Aurelia3, on the contrary, seek each other, and 
commonly herd together. 

Fig. 50. Aurelia flavidula, seen from above 5 o mouth, e e e e eyes, mm mm lobes of the mouth, 
oo oo ovaries, tttt tentacles, w w ramified tubes. (Agassiz.) 



44 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



The Campanella. (Campanella pachyderma A. AG.) 

The Campanella (Fig. 51) is a pretty little Jelly-fish, not 

larger than a pin s head, 
reproduced directly from 
eggs, without passing 
through the Hydroid 
stage. During its early 
stages of growth it prob 
ably remains attached to 
floating animals, thus 
leading a kind of para 
sitic existence ; but as 
its habits are not accu 
rately known, this cannot 
be asserted as a constant 
fact respecting them. 
The veil in this Jelly 
fish is very large, form 
ing pendent pouches 
hanging from the cir 
cular canal (see Fig. 
51), and leaving but 
just room enough for 
the passage of the pro 
boscis between the folds. 
It may not be amiss to 
introduce here a general 
account of this organ, 
which occurs in many 
of the Medusae, though 
it has very different pro 
portions in the various kinds. It is a delicate membrane, hang 
ing from the circular tube, so as partially to close the mouth of 
the bell, leaving a larger or smaller opening for the passage 
of the water, which is taken in and forced out again by the alter 
nate expansions and contractions of the bell. 

Fig. 51. Campanella seen in profile ; greatly magnified. 
Tig. 62. Same, seen from below. 




CIRCE. 45 

There are but four chymiferous tubes in the Campanella, 
and four stiff tentacles, which in consequence of the pecu 
liar character of the veil appear, when the animal is seen in 
profile, to start from the middle of the disk. The ovaries con 
sist of eight pouches, placed near the point of junction of the four 
chymiferous tubes. (Fig. 52.) This little Medusa is of a dark 
yellowish color with brownish ocellated spots, scattered profusely 
over the upper part of the disk. 

Circe. (TracJiynema digitale A. AG.) 

Among the Jelly-fishes, the position of which is somewhat 
doubtful, is the Circe (Fig. 53), differing greatly in outline 
from the ordinary Jelly- Fig. 53. 

fishes. As may be seen 
in Figure 53, the bell 
forms but a small por 
tion of the animal ; it rises 
in a sharp cone on the 
summit, thinning out at 
the lower edge, to form 
the large cavity in which 
hangs the long proboscis 
and the eight ovaries, four 
of which may be seen in 
Fig. 53 crowded with eggs. 
The Circe differs in con 
sistency, as well as in form, 
from other Jelly-fishes. It 
is hard and horny to the 
touch, and the veil, usu 
ally so light and filmy, is 
here a thick folded membrane, which at every stroke of the ani 
mal forces the water in and out of the cavity. It is very active, 
moving by powerful jerks, each one of which throws it far on its 
way. It advances usually in straight lines ; or, if it wishes to 
change its direction, it drives the water out of the veil suddenly 

Fig. 53. Trachynema digitale ; about twice the natural size. 




46 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



on one side or the other, so as to shoot off, sometimes at right 
angles with its former path. Four large pedunculated eyes, hid 
den in the figure by the tentacles, stand out prominently from the 
circular tube. When the animal is in motion, the tentacles are 
carried closely curled around the edge of the disk, as in Fig. 
53, where the Circe is represented under a magnifying power 
of two and a half diameters. This Jelly-fish is of a delicate rose 
color, the tentacles assuming, however, a dark-purple tint at 
their extremities when contracted. 



Fig 54. 



z&mji 
4^r 

W 



i^yi i 

fMWil , 



Lucernaria. (Halyclistus auricula CLARK.) 

One of the prettiest and most graceful, as well as one of the 
most common of our Jelly-fishes, is the Lucernaria (Fig. 54). It 

has such an extraordinary con 
tractility of all its parts, that it is 
not easy to describe it under any 
definite form or position, since 
both are constantly changing ; 
but perhaps of all its various at 
titudes and outlines none are 
more normal to it than those 
given in Fig. 54. It frequently 
raises itself in the upright po 
sition represented here by the 
individual highest on the stem, 
spreading itself in the form of a 
perfectly symmetrical cup or vase, 
the margin of which is indented by a succession of inverted scal 
lops, the point of junction between every two scallops being 
crowned by a tuft of tentacles. But watch it for a while, and 
the sides of this vase turn backward, spreading completely open, 
till they present the whole inner surface, with the edges even 
curved a little downward, drooping slightly, and the proboscis 
rising in the centre. In such an attitude one may trace with 
ease the shape of the mouth, the lobes surrounding it, as well as 
the tubes and cavities radiating from it toward the margin. A 



Fig. 54. Group of Luceraariie attached to eel-gra?s ; natural size. 



LUCERNARIA. 47 

touch is, however, sufficient to make it close upon itself, shrink 
ing together in the attitude of the third individual in Fig. 54, or 
even drawing its tentacles completely in, and contracting all its 
parts till it looks like a little ball hanging on the stem. These 
are but a few of its manifold changes, for it may be seen in every 
phase of expansion and contraction. Let us now look for a mo 
ment at the details of its structure. The resemblance to a cup or 
vase, as in the upper figure of the wood-cut (Fig. 54), is decep 
tive ; for a vase is hollow, whereas the Lucernaria, though so deli 
cate and transparent that its upper surface, when thus stretched, 
seems like a mere film, is nevertheless a solid gelatinous mass, 
traversed by certain channels, cavities, and partitions, but other 
wise continuous throughout. The peduncle by which it is at 
tached is but an extension of the floor of a gelatinous disk, cor 
responding to that of any Jelly-fish. Four tubes pass through the 
whole length of this peduncle, and open into four chambers, 
dividing the digestive cavity above into as many equal spaces. 
(Fig. 55.) These spaces are Fiff 55 

produced by folds in the up 
per floor of the disk, uniting 
it to the lower floor at giv 
en distances, and forming so 
many partition-walls, dividing 
the digestive sac into four dis 
tinct cavities. These lines of 
juncture between the two 
floors, where the partitions oc 
cur, produce the four radial 
ing lines, running from the 
proboscis to the margin of the 
disk, on the upper surface. (Fig. 55.) The triangular figures, 
running from the mouth to each cluster of tentacles, are pro 
duced by the ovaries, which consist of distinct pouches or bags 
attached to the upper surface of the disk, and hanging down into 
the cavities below ; every little dot within these triangular spaces 
represents such a bag. Each bag is crowded with eggs, which 
drop into the digestive cavity at the spawning season, and are 

Fig 55. Lucernaria seen from the mouth side 




48 MARINE ANIMALS OF MASSACHUSETTS BAY. 

passed out at the mouth. The tentacles always grow in clus 
ters, but are nevertheless arranged according to a regular order. 
They are club-shaped at their extremities, but are hollow 
throughout, opening into the chambers of the digestive cavity, 
two of the clusters thus being connected with each chamber. 
Their chief office seems to be to catch the food and convey it to 
the mouth, though they may also be used as a kind of suckers, 
and the animal not unfrequently attaches itself by means of these 
appendages. Between every two clusters of tentacles will be ob 
served a short, single appendage, of an entirely different appear 
ance. These are the so-called auricles, and though so unlike 
tentacles in the adult animal, when in their earlier stages (Fig. 
56) they resemble each other closely. But as their development 
goes on, the tentacles stretch out into longer, 
more delicate flexible organs, while the auri 
cles remain short and compact throughout 
life. They contain a slight pigment spot 
representing an eye, though how far it serves 
the purpose of vision remains doubtful. 
They are chiefly used by the animal as a 
means of adhering to any surface upon which 
it may wish to fasten itself; for the Lucer- 
naria, though usually found attached to eel-grass in shoal water, 
has the power of independent motion, and frequently separates 
from its resting-place, floating about freely in the water for a while, 
or attaching itself anew by means of the auricles and tentacles 
upon some other object. The color of this pretty Acaleph varies 
from a greenish hue to green, with a faint tinge of red, or to a 
reddish brown. One of its commonest and most exquisite tints is 
that of a pale aqua-marine. It may be found along our shores 
wherever the eel-grass grows, and as far out as this plant extends. 
It thrives admirably in confinement, and for this reason is espe 
cially adapted to the aquarium. 

Fig. 56 Young Lucernaria ; magnified 







Library 




HYDROIDS. 



HYDROIDS. 



UNDER this order, the general character of which has already 
been explained in the introductory chapter on Acalephs, are in 
cluded a number of groups which, whether as Hydroid commu 
nities in their earlier phases of existence, or as free swimming 
Medusae in their farther development, challenge our admiration, 
both for their beauty of form and color, and their grace of motion. 
Some of them are so minute that they escape the observation of 
all but those who are laboriously seeking for the hidden treas 
ures of the microscopic world, but the greater number are large 
enough to be readily found by the most inexperienced collector, 
when his attention is once drawn to them ; and he may easily 
stock his aquarium with these pretty little communities, and 
even trace the development of the Jelly-fishes upon them. 

To the Hydroids belong the Campanularians, the Sertularians, 
and the Tubularians. Some examples of each, as represented on 
our shores, will be found under their different heads, accompa 
nied with full descriptions. There is another group usually con 
sidered as distinct from Hydroids, and known as a separate order 
among Acalephs, under the name of Siphonophorae, but included 
with them here in accordance with the views of Vogt, Agassiz, 
and others, in whose opinion they differ from the ordinary Hy 
droid communities only in being free and floating, instead of 
fixed to the ground. Some new facts, published here for the 
first time, tend to sustain the accuracy of this classification.* 
With these few preliminary remarks to show the connection of 
the order, let us now look at some of the animals belonging to it 
more in detail. 

Campanularians . 

All the Campanularians, of which Oceania (Fig. 68), Clytia 
(Fig. 73), and Eucope (Fig. 61) form a part, belong among 
those little shrub-like communities of animals called Hydroids, 

* See Chapter on Nanomia. 

7 




50 MARINE ANIMALS OF MASSACHUSETTS BAY. 

from which most of our Jelly-fishes are developed. They differ 
in one essential feature from the Tubularians. (Fig. 93.) The 
whole stem, from summit to base, is enveloped in a horny sheath, 
extending around both the fertile and sterile individuals of the 
community, and forming a network at the base of the stem, 
which serves as a kind of foundation for the whole stock. To 
the naked eye such a community looks like a tiny shrub (see 
Fig. 57), with the branches growing in regular alternation on 
either side of the stems. The reproductive calycles, i.e. the pro 
tecting envelopes covering the young Medusae, usually arise in 
the angles of the branches formed by a prolongation of the 
sheath. These calycles or bells, as they are called, assume a 
great variety of shapes, elliptical, round, pear-shaped, or ringed 
like the Clytia. (Fig. 72.) In one such bell there may be no 
less than twenty or thirty Medusae developed one below the 
other ; when ready to hatch, the calycle bursts and allows them 
to escape. 

Eucope. (Eucope diapliana AG.) 

In Figs. 60 and 61 we have a representation of our little 
Eucope, one of the prettiest of the Jelly-fishes belonging to this 

Fig. 57. Fig. 58. 





group ; Fig. 57 represents the Hydroid from which it arises ; a 
single branch with the reproductive bell being magnified in Fig. 



Fig. 57. Hyrtrarium of Eucope ; natural size 
Fig. 58. Portion of Fig. 57 ; magnified. 



EUCOPE. 



51 



58. In Fig. 59 is seen a portion of the Jelly-fish disk, with the 
fringe of tentacles highly magnified. The disk of the Eucope 
(Fig. 60) looks like a shallow bell, of which the proboscis often 
seems to form the handle ; for the disk has such an extraordi- 



Fig. 59. 



Fig. 60. 





nary thinness that it turns inside out with the greatest ease, so 
that the inner surface may become at any moment the outer one, 
with the proboscis projecting from it, as in Fig. 60, while the next 
movement of the animal may reverse its whole position, and the 
proboscis then hangs down from the inside, as in other Jelly- 
fishes. (See Fig. 61.) 

The tentacles are solid and stiff like little hairs, and two of 
them, in each quarter-segment of the disk, have small concretions 

Fig. 61 Fig. 62. 





at the base, which are no doubt eye-specks. (See Fig. 62.) 
Along the chymiferous tubes little swellings are developed, which 
increase gradually, and become either ovaries or spermaries, 
according to the sex of the animal. (Fig. 63.) In the adult the 
genital organs hang down, like elongated bags, from the chy- 

Fig. 59. Part of marginal tube and tentacles of Eucope, greatly magnified ; e eye-speck, b base of 
tentacle, r reentering base of tentacle. 
Fig. 60. Young Eucope ; magnified. 
Fig. 61. Adult Eucope seen in profile ; magnified. 
Fig. 62. Quarter disk of Fig 60, seen from below ; e e tentacles bearing eye-speck. 



52 MARINE ANIMALS OF MASSACHUSETTS BAY. 

miferous tubes. (Fig. 64.) The tentacles are numerous, multi 
plying to about a hundred and ninety-two in the adult, and in 
creasing according to the numerical law to be explained in the 
description of the Oceania. 

This little Jelly-fish is one of the most common in our Bay. 

Fig. 63. Fig. 64. 





There is not a night or day when they cannot be taken in large 
numbers, from the early spring till late in the autumn ; and as 
the breeding season lasts during the whole of that period, they 
are found in all possible stages of growth. In consequence of 
this, the course of their development, and the relation between 
the different prises of their existence as Hydroids, and afterwards 
as Acalephs, are well known, though the successive steps of their 
growth have not been traced connectedly, as in some of the other 
Jelly-fishes, the Tima or Melicertum, for instance. The process 
is, however, so similar throughout the class of Hydroids, that, 
having followed it from beginning to end in some of the groups, 
we have the key to the history of others, whose development has 
not been so fully traced. The eggs laid by the Eucope in the 
autumn develop into planula3, which acquire their full size as 
Hydroid communities toward the close of the winter, and the 
development of the young Medusae upon them, as described 
above, begins with the opening spring. 

Fig. 63. Quarter-disk of young Eucope, older than Fig. 62, with a second set of tentacles (2) be 
tween the first set (1). 
Fig. 64. Magnified quarter-disk of adult Eucope. 



OCEANIA. 53 

Oceania. (Oceania languida A. AG.) 

The Oceania (Fig. 68) is so delicate and unsubstantial, that 
with the naked eye one perceives it only by the more prominent 
outlines of its structure. "We may see the outline of the disk, but 
not the disk itself ; we may trace the four faint thread-like lines 
produced by the radiating tubes traversing the disk from the 
summit to the margin ; and we may perceive, with far more dis 
tinctness, the four ovaries attached to these tubes near their base ; 
we may see also the circular tube uniting the radiating tubes, 
and the tentacles hanging from it, and we can detect the edge of 
the filmy veil that fringes the margin of the disk. But the sub 
stance connecting all these organs is not to be distinguished from 
the element in which it floats, and the whole structure looks like 
a slight web of threads in the water, without our being able to 
discern by what means they are held together. Under the mi 
croscope, however, the invisible presently becomes visible, and we 
find that this Jelly-fish, like all others, has a solid gelatinous 
disk. 

Let us begin with its earlier condition. When it first escapes 
from the parent Hydroid stock, the Oceania is almost spherical 
in form. (See Fig. 65.) The disk is divided by four chymiferous 
tubes, running from the summit to the margin, where they meet 
the circular tube in which they all unite. At this time, it has 
but two well-developed tentacles, opposite each other on the mar- 
Fig. 65. 





gin of the disk, just at the base of two of the chymiferous tubes 
(Fig. 66), while two others are just discernible in a rudimentary 

Fig. 65. Young Oceania just escaped from its reproductive calycle ; magnified. 
Fig. 66. The same as Fig. 65, from below, still more magnified ; t long tentacles, t rudimentary ten 
tacle, e eye-speck on each side of base of tentacles. 




54 MARINE ANIMALS OF MASSACHUSETTS BAY. 

state, forming slight projections at tlie base of the two other 
tubes. Fig. 66 gives a view of the animal from below, at this 
stage of its growth, while Fig. 65 shows it in profile. It will be 
seen by the latter how very spherical is the outline of the disk at 
this period, while the proboscis, in which are placed the mouth 
and digestive cavity, is quite long, and hangs down considerably 
below the lower surface of the disk. As the animal advances in 
age the disk loses its spherical outline, and becomes much flat 
tened, as may be seen in Fig. 67. It may be well to introduce 

here some explanation of the law ac- 

Fig. 67. r 

cording to which the different sets of 
tentacles follow each other in succes 
sive cycles of growth, since it is a law 
of almost universal application in Jelly- 
fishes and Polyps ; and, owing to the 
smaller number and simpler arrange 
ment of the tentacles in Oceania, it may be more easily analyzed 
in them than in many others, where the number and complication 
of the different sets of tentacles make it very difficult to trace 

their relation to 
each other dur 
ing their successive 
growth. We have 
seen that the Oce 
ania begins life 
with only two ten 
tacles. These form 
the first set, and 
are marked with 
the number 1 in 
the subjoined dia 
gram, which gives 
the plan of all the 
different sets in 
their regular order. The second set, marked 2, consists also of 
two, which are developed at equal distances between the first two, 
i. e. at right angles with them. The third set, however, marked 3, 

Fig. 67. Young Oceania, older than Fig. 65 ; magnified. 




OCEANIA. 55 

consists of four, as do all the succeeding sets, and they are de 
veloped between the first and second. The fourth set comes in be 
tween the first and third ; the fifth between the third and second ; 
the sixth between the first and fourth ; the seventh between the 
fifth and second ; the eighth between the third and fourth ; the 
ninth between the fifth and third. The ultimate number of ten 
tacles in the Oceania is thirty-two, or sometimes thirty-six, and the 
cycles always in twos or multiples of two. But whatever be the 
number included in the successive sets of tentacles, and the 
unit for the first set ranges from two to forty-eight, the law in 
different kinds of Jelly-fishes is always the same, the youngest 
set always forming between the oldest preceding set. Thus the 
fourth set comes in between the first and third, and the fifth be 
tween the second and third, the intervals occupied now by the 
fourth set, being limited by the first set of tentacles 011 one side, 
and by the third set on the other side, while the intervals occu 
pied by the fifth set are bounded by the second and third sets. 

The little spheres represented be 
tween the tentacles on the mar 
gin of the disk, in Figs. 65-67, 
are eye-specks, and these continue 
to increase in number with age ; 
in this the Oceania differs from 
the Eucope, in which it will be 
remembered there were but two 
eye-specks in each quarter-seg 
ment of the disk throughout 
life. Fig. 68 represents the adult 
Oceania in full size, when it aver 
ages from an inch and a half to two 
inches in diameter. It is slow and languid in its movements, 
coming to the surface only in the hottest hours of the sum 
mer days ; at such times it basks in the sun, turning lazily 
about, and dragging its tentacles after it with seeming effort. 
Sometimes it remains for hours suspended in the water, not 
moving even its tentacles, and offering a striking contrast to 
its former great activity when young, and to the lively little 

Fig. 68. Adult Oceania ; natural size. 





56 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Eucope, which darts through the water at full speed, hardly stop 
ping to rest for a moment. If the Oceania be disturbed it flattens 
its disk, and folds itself up somewhat in the shape of a bale (see 
Fig. 69), remaining perfectly still, with the tentacles stretching 
in every direction. When the cause of alarm is removed, it 

gently expands again, re 
suming its natural outline 
and indolent attitudes. The 
number of these animals is 
amazing. At certain sea 
sons, when the weather is 
favorable, the surface of the 
sea may be covered with 
them, for several miles, so 
thickly that their disks 
touch each other. Thus they remain packed together in a dense 
mass, allowing themselves to be gently drifted along by the 
tide till the sun loses its intensity, when they retire to deeper 
waters. Some points, not yet observed, are still wanting to com 
plete the history of this Jelly-fish. By comparing such facts, 
however, as are already collected respecting it, with our fuller 
knowledge of the same process of growth in the Eucope, Tima, 
and Melicertum, we may form a tolerably correct idea of its de 
velopment. It is hatched from a Campanularia. 

Clytia. (Clytia bicophora AG.) 

In Figs. 70-73 we have the Acalephian and Hydroid stages 
of the Clytia (Fig. 73), another very pretty little Jelly-fish, closely 
allied to the Oceania. When first hatched, like the Oceania, it is 
very convex, almost thimble-shaped (see Fig. 70), but a little 
later the disk flattens and becomes more open, as in Fig. 71. In 
Fig. 72, we have a branch of the Hydroid, a Campanularia, 
greatly magnified, with the annulated reproductive calycle at 
tached to it, and crowded with Jelly-fishes ready to make their 
escape as soon as the calycle bursts. The adult Clytia (Fig. 73) 
is somewhat smaller and more active than the Oceania, and 

Fig. 69. Attitude assumed by Oceania when disturbed. 



CLYTIA. 



57 



is easily recognized by the black base of its tentacles, at their 
point of juncture with the margin of the disk. It is more corn- 
Fig- 70. Fig. 71. 





monly found at night, than in the day-time, being nocturnal in 
its habits. 

Fig. 72. Fig. 73. 





Zygodactyla. (Zygodactyla groenlandica AG.) 

Little has been known, and still less published, of this remark 
able genus of Jelly-fish (Figs. 74, 75) up to the present time. 
The name Zygodactyla, or Twinfinger, was given to it by Brandt, 
from drawings made by Mertens, who had some opportunity of 
studying it in his journey around the world. These drawings 

Fig. 70. Young Clytia just escaped from the reproductive calycle. 
Fig. 71. Clytia somewhat older than Fig. 70. 
Fig. 72 Magnified portion of Hydrarium of Clytia. 
Fig. 73. Adult Clytia ; twice natural size. 
8 



58 MARINE ANIMALS OF MASSACHUSETTS BAY. 

were published in the Transactions of the St. Petersburg Academy. 
In the year 1848 Professor Agassiz read a paper upon one of the 
species of this genus belonging to our coast, before the American 
Academy, in which he called it Rhacostoma, not being aware 
that it had already received a name, and gave some account of 
its extraordinary phosphorescent properties. The name Rhacos 
toma must of course yield to that of Zygodactyla, which has a 
prior claim. 

The average size of this Jelly-fish when full grown is from 
seven to eight inches in diameter ; sometimes it may measure 

Fig. 74. 




even ten or eleven, but this is rather rare. The light-violet col 
ored disk is exceedingly delicate and transparent, its edge being 
fringed with long fibrous tentacles, tinged with darker violet at 
their point of juncture with the disk, and hanging down a yard 
and more when fully extended, though they vary in length ac 
cording to the size of the specimen, and, in consequence of their 
contractile power, may seem much shorter at some moments than 
at others. The radiating tubes in this Jelly-fish are exceedingly 

Fig. 74. Zygodactyla seen from above. 



ZYGODACTYLA. 59 

numerous, the whole inner surface of the disk being ribbed with 
them. (See Figs. 74 and 75.) The ovaries follow the length of 
the tubes, though they do not extend quite to their extremity, 
where they join the circular tube around the margin of the disk ; 
nor do they start exactly at the point where the tubes diverge 
from the central cavity, but a little below it. (Fig. 74.) Each 
ovary consists of a long, brownish, flat bag, split along the mid 
dle, so closely folded together that it seems like a flat blade 
attached along the length of the tube. Perhaps a better compar 
ison would be to a pea-pod greatly elongated, with the edges split 
along their line of juncture, and attached to a tube of the same 
length. The ovaries are not perfectly straight, but slightly wav 
ing, as may be seen in Fig. 74, and these undulations are stronger 
when the ovaries are crowded with eggs, as is the case at the 
time of spawning. 

The large digestive cavity hangs from the centre of the under 
side of the disk (Fig. 75), terminating in the proboscis, which, in 

Fig. 75. 




this kind of Jelly-fish, is short in proportion to the diameter of 
the disk, while the opening of the mouth is very large. (Fig. 74.) 
It is unfortunate that a variety of inappropriate names, likely to 
mislead rather than aid the unscientific observer, have been ap 
plied to different parts of the Jelly-fish. What we call here di 
gestive cavity, proboscis, and mouth, are, in fact, parts of one 
organ. An exceedingly delicate, transparent, filmy membrane 
hangs from the under side of the disk ; that membrane forms the 
outer wall of the digestive cavity, which it encloses ; it narrows 

Fig. 75. Zygodactyla seen in profile. 



60 MARINE ANIMALS OF MASSACHUSETTS BAY. 

toward its lower margin, leaving open the circular aperture called 
the mouth ; this narrowing of the membrane is produced by a 
number of folds in its lower part, while at its margin these folds 
spread out to form ruffles around the edge of the mouth, and 
these ruffles again extend into the long scalloped fringes hanging 
down below. 

The motion of these Jelly-fishes is very slow and sluggish. 
Like all their kind, they move by the alternate dilatation and 
contraction of the disk, but in the Zygodactyla these undulations 
have a certain graceful indolence, very unlike the more rapid 
movements of many of the- Medusae. It often remains quite mo 
tionless for a long time, and then, if you try to excite it by dis 
turbing the water in the tank, or by touching it, it heaves a slow, 
lazy sigh, with the whole body rising slightly as it does so, and 
then relapses into its former inactivity. Indeed, one cannot help 
being reminded, when watching the variety in the motions of the 
different kinds of Jelly-fishes, of the difference of temperament in 
human beings. There are the alert and active ones, ever on the 
watch, ready to seize the opportunity as it comes, but missing it 
sometimes from too great impatience ; and the slow, steady peo 
ple, with very regular movements, not so quick perhaps, but as 
successful in the long run ; and the dreamy, indolent characters, 
of which the Zygodactyla is one, always floating languidly about, 
and rarely surprised into any sudden or abrupt expression. One 
would say, too, that they have their aristocratic circles ; for there 
is a delicate, high-bred grace about some of them quite wanting 
in the coarser kinds. The lithe, flexible form of the greyhound 
is not in stronger contrast to the heavy, square build of the bull 
dog, than are some of the lighter, more frail species of Jelly-fish 
to the more solid and clumsy ones. Among these finer kinds we 
would place the Tima. (Fig. 76.) 

Tima. (Tima formosa AG.) 

One s vocabulary is soon exhausted in describing the dif 
ferent degrees of consistency in the substance of Jelly-fishes. 
Delicate and transparent as is the Tima, it has yet a certain 
robustness and solidity beside the Oceania, described above. In 



TIMA. 



61 



fact, all are gelatinous, all are more or less transparent, and it is 
not easy to describe the various shades of solidity in jelly. Per 
haps they may be more accurately represented by the impression 
made upon the touch than upon the sight. If, for instance, you 
place your hand upon a Zygodactyla, you feel that you have 
come in contact with a substance that has a positive consistency ; 
but if you dip your finger into a bowl where a Tima is swimming, 
and touch its disk, you will feel no difference between it and the 

Fig. 76. 




Library 




California- 



in which it floats, and will not be aware that you have 
reached it till the animal shrinks away from the contact. 

The adult Tima, represented in Fig. 76, is not more than an 
inch and a half or two inches in diameter. Instead of count 
less tubes diverging from the digestive cavity to the margin of 
the disk, as in the Zygodactyla, there are but four. The di 
gestive cavity in the Tima is much smaller than in the Zygo 
dactyla, and is placed at the end of the proboscis, which is long, 
and hangs down far below the disk. This removal of the diges 
tive cavity to the extremity of the proboscis gives to the tubes 

Fig. 76. Tima; half natural size. 

Fig. 77. One of the lips of the mouth at the extremity of the long proboscis 5 m mouth, d digestive 
cavity, c chymiferous tube. 



62 MARINE ANIMALS OF MASSACHUSETTS BAY. 

arising from it a very different and much sharper curve than 
they have in the Zygodactyla. In the Tima they start from the 
end of the proboscis, as may be seen in the wood-cut (Fig. 76), 
and then turn abruptly off, when they arrive at the under surface 
of the disk, to reach its margin. The disk has, as usual, its veil 
and its fringe of tentacles ; the tentacles in the full-grown Tima 
are few, seven in all the four intermediate spaces between the 
tubes, with one at the base of each tube, making thirty-two in 
all. The ovaries, which are milk-white, follow the line of the 
tubes, as in the Zygodactyla, and have very undulating folds 
when full of eggs. The tubes meet in the digestive cavity, 
Fig<78 . the margin of which 

spreads out to form 
four ruffled edges that 
hang down from it. 
One of these ruffles, 
considerably magni 
fied, is represented 
in Fig. 77. In Fig. 
78 we have a portion 
of the Hydroid stock 
from which this Jelly 
fish arises, also great 
ly magnified. The 
Tima is very active, 
yet not abrupt in its 
motions ; but when in good condition it is constantly moving 
about, rising to the surface by the regular pulsations of the disk, 
or swimming from side to side, or poising itself quietly in the 
water, giving now and then a gentle undulation to keep itself in 
position. 

Though not a very frequent visitor of our shores, the appear 
ance of the Tima is not limited by the seasons, since they are 
found at all times of the year. It is a fact, unexplained as yet, 
that the Tima and many other Jelly-fishes are never seen except 
when full grown. What may be the haunts and habits of these 
animals from the time of their hatching till they make their 

Fig. 78. Magnified head of Hydrarium of Tima. 




MELICERTUM. 63 

appearance again in the adult condition, is not known, though it 
is probable that they remain at the bottom during this period, 
and only come to the surface to spawn. This impression is con 
firmed by the observations made upon a very young Cyanea 
which was kept for a long time in confinement ; but a question 
of this kind cannot of course be settled by a single experiment.* 

Melicertum. (Melicertum campanula PER. et LES.) 

A pretty Medusa, smaller and far more readily obtained than 
the Tima, is the Melicertum. (Fig. 80.) Its disk has a yellow 
ish hue, and from its margin hangs a heavy row of yellow tenta 
cles, while the eight ovaries (Fig. 79) are of a darker shade of 
the same color. This little gold 
en-tinted Jelly-fish, moving through 
the water with short, quick throbs, 
produced by the rapid rise and fall 
of the disk, is a very graceful ob 
ject. Its bright color, made partic 
ularly prominent by the darker un 
dulating lines of the ovaries, which 
become very marked near the spawn 
ing season, renders it more conspic 
uous in the water than one would 
suppose from its size ; for it does not measure more than an 
inch in height when full grown. (See Fig. 80.) 

* Since the above was written, I have had an opportunity of learning some ad 
ditional facts respecting the habits of the young Cyanea, which may, perhaps, apply 
to other Jelly-fishes also. Having occasion to visit the wharves at Provincetown at 
about four o clock one morning, I was surprised to find thousands of the spring brood 
of Cyanese, hitherto supposed to pass the early period of their existence wholly in 
deep water, floating about near the surface. They varied in size, some being no 
larger than a three-cent-piece, while others were from an inch in diameter to three 
inches. It would seem that they make their appearance only during the earliest 
morning hours, for at seven o clock, when I returned to the same spot, they had all 
vanished. It may be that other young Medusce have the same habits of early rising, 
and that instead of coming to bask in the midday sunshine, like their elders, they 
prefer the cooler hours of the dawn. (A Ayassiz.} 

Fig. 79. Melicertum campanula seen from above ; m mouth, o o ovaries, 1 1 tentncleg. (Ajasniz.) 




64 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Development of Melicertum and Tima. 

In the Melicertum and Tima we have had the good fortune to 
trace the process by which the eggs are changed into Hydroid 
communities. If any one has a curiosity to follow for themselves 
this singular history of alternate generations, the Melicertum is a 
good subject for the experiment, as it thrives well in confinement. 

Fig. 80. 




After keeping a number of them in a large glass jar for a couple 
of days at the time of spawning, it will be found that the ovaries, 
which were at first quite full of eggs, are emptied, and that a num 
ber of planulae are swimming about near the bottom of the vessel. 
After a day or two the outline of these planulse, spherical at first, 
becomes pear-shaped (see Fig. 81), and presently they attach 
themselves by the blunt end to the bottom of the jar. (Fig. 82.) 
Thus their Hydroid life begins ; they elongate gradually, the 
horny sheath is formed around them, tentacles arise on the upper 

Fig. 80. Melicertum seen in profile ; natural size. 



LAOMEDEA. 65 

end, short and stunted at first, but tapering rapidly out into fine 
flexible feelers, the stem branches, and we have a little Hydroid 
community (Fig. 83), upon which, in the course of the following 
spring, the reproductive calycles containing the Medusa buds will 

Fig. 83. 



Fig. 82. 






be developed, as in the case of the Eucope and Clytia. The 
Tima passes through exactly the same process, though the shape 
of the planula3 and the appearance of the young differ from that 
of the Melicertum, as may be seen in Fig. 78, where a single 
head of the Tima Hydroid, greatly magnified, is represented. 
By combining the above observations upon the development of 
the Hydroids of the Melicertum and Tima with those previously 
mentioned upon the young Medusa arising from reproductive 
calycles in the Eucope and Clytia, we get a complete picture of 
all the changes through which any one of these Hydroid Medusas 
passes, from its Hydroid condition to the moment when it enters 
upon an independent existence as a free Jelly-fish. 

(Laomedea amphora AG.) 

The Medusae of the Campanularians are not all free. On the 
contrary, in many of the species they always remain attached to 
the Hydroid, never attaining so high a development as the free 
Medusae, and withering on the stem after having laid their eggs. 

Fig. 81. Planula of Melicertum ; magnified. 
Fig. 82. Cluster of planulse just attached to the ground. 
Fig. 83. Young Hydrarium developed froia planulaj ; magnified. 
9 



66 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Such is the Laomedea amphora, quite common on all the bridges 
connecting Boston with the country, where, on account of the 
large amount of food brought down from the sewers by the river, 
they thrive wonderfully, growing to a great size, sometimes meas 
uring from a foot to eighteen inches in height. 



Sertularians. 

The Sertularians form another group of Hydroids closely 
allied to the Campanularians, though differing from them in the 
arrangement of the sterile Hydras upon the stem. Among these 
one of the most numerous is the Dynamena {Dynamena pumila 
Lamx., Fig. 84), which hangs its yellowish fringes from almost 
every sea-weed above low-water-mark. It is especially thick and 
luxuriant on the fronds of our common Fucus vesiculosus. The 
color is usually of a pale yellow, though sometimes it is nearly 
white, and when first taken from the water it has a glittering 
look, such as a white frost leaves on a spray of grass. Fig. 84 

Fig. 85. 





represents such a cluster in natural size, while Fig. 85 shows a 
piece of the stem highly magnified, with a reproductive calycle 
attached to the side of a sterile Hydra stem. Many of these 
Sertularian Hydroids assume the most graceful forms, hanging 
like long pendent streamers from the Laminaria, or in other 
instances resembling miniature trees. One of these tree-like 

Fig. 84. Colony of Dynamena pumila ; natural size. 
Fig. 85. Magnified portion of Fig. 84. 



TUBULARIANS. 67 

Sertularians (JDyphasia, rosacea Ag.), abundant on all rocks in 
sheltered places immediately below low-water-mark, is repre 
sented in Fig. 86. In both these Sertularians the Medusae wither 
011 the stock, never becoming free. The free Medusae of the 



Fig. 86. Fig. 87. 





Sertularians are only known in their adult condition in a single 
genus, which is closely allied to Melicertum, and which is pro 
duced from a Hydroid genus called Lafoea. Fig. 87 repre 
sents one of these young Sertularian Medusae (Lafoea cornuta 
Lainx.). 

Tubularians. 

In the Sertularian and Campanularian Hydroids we have found 
that the communities consist generally of a large number of small 
individuals, so small, indeed, that it is hardly possible at first 
glance to distinguish the separate members of these miniature 
societies. Among the Tubularians, on the contrary, the commu 
nities are usually composed of a small number of comparatively 
large individuals ; and indeed these Hydroids may even grow 
singly, as in the case of the Hybocodon (Fig. 104), which attains 
several inches in height. There is also another general feature 
in which the Tubularians differ from both the other groups of 
Hydroids. In the latter, the horny sheath which encloses the 
stem extends to form a protecting calycle around the Hydra 

Fig. 86. Dyphasia rosacea, natural size. 
Fig. 87. Medusa of Lafaea. 



68 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



heads. This protecting calycle is wanting round the heads 
of the Tubularians, though their stems are surrounded by a 
sheath. 



Sarsia. (Coryne mirabilix AG.) 

Among the most common of our Tubularians is a small, mossy 
Hydroid (Fig. 88), covering the rocks between tides, in patches 
of several feet in diameter. Fig. 89 represents a single head 
from this little mossy tuft greatly magnified, in which is seen the 
medusa bud arising from the stem by the process already de 
scribed in- the other Hydroids. In Fig. 90 we have the little 



Fig. 88. 



Fig. 00. 





Jelly-fish in its adult condition, about the size of a small walnut, 
with a wide circular opening, through which passes the long pro- 
Fig. 88. Colony of Coryne ; natural size. (Agassix.) 

Fig. 89. Magnified head of Coryne 5 a stem, t tentacles, o mouth, v body, d Medusa. (Agassiz.) 
Fig. 90. Free Medusa of Coryne. (Ayassiz.) 



SARSIA. 69 

boscis, hanging from the under surface of the disk to a consider 
able distance below its margin. The four tentacles are of an 
immense length when compared to the size of the animal. As a 
general thing, the tentacles are less numerous in the Tubularian 
Medusa3 than in those arising from other Hydroids ; they want 
also the singular limestone concretions found at the base of the 
tentacles in the Campanularian Medu 
sae. In Fig. 91 we have one of the 
Tubularian Medusas (Turrit vesicaria 
A. Ag.) which has a rather larger 
number of tentacles than is usual 
among these Jelly-fishes. We never 
find the tentacles multiplying almost 
indefinitely in them, as in Zygodac- 
tyla and Eucope. The little Jelly-fish 
described above is known as Sarsia, 
while its Hydroid is called Coryne. 
These names having been given to 
the separate phases of its existence 
before their connection was understood, 
and when they were supposed to rep 
resent two distinct animals. They are 
especially interesting with reference 
to the history of Hydroids in general, 
because they were among the first of these animals in whom 
the true relation between the different phases of their exist 
ence was discovered. Lesson named the Sarsia after the great 
Norwegian naturalist, Sars, to whom we owe so large a part of 
what is at present known respecting this curious subject of alter 
nate generations. 



JBougainvillia. (BougawviUia superciliaris AG.) 

The Bougainvillia (Fig. 92), is one of our most common 
Jelly-fishes, frequenting our wharves as well as our sea-shore 
during the spring. The tentacles are arranged in four bunches 

Fig. 91. Turris vesicaria ; natural size. 




70 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



or clusters at the junction of the radiating tubes with the cir 
cular tube, from which they may be seen extending in every 



Fig. 92. 





direction whenever these animals re 
main quietly suspended in the water, 
a favorite attitude with them, and 
one which they retain sometimes for 
days, seeming to make no effort be 
yond that of gently playing their ten 
tacles to and fro (Fig. 92). These 
tentacles are capable of immense ex 
tension, sometimes to ten or fifteen 
times the diameter of the bell. The 
proboscis is not simple as in the Sar- 
sia, but looks like a yellow urn sus 
pended at its four corners from the 
chymiferous tubes. The oral opening 
is entirely concealed by clusters of 
shorter tentacles surrounding the 
mouth in a close wreath, on which the 
eggs are supported. A highly magni 
fied branch of the Hydroid stock from 



Fig. 92. Bougainvillia ; magnified. 

Fig. 93. Hydrarium of Bougainvillia ; magnified. 



BOUQAINVILLIA. 



71 



which this Medusa arises is represented in Fig. 93. There wo 
see the little Jelly-fishes in different degrees of development on 

Fig. 94. Fig. 95. 





the stem, while in Figs. 94 97 they are given separately and 
still more enlarged. In Fig. 94 the outline of the Jelly-fish is 
still oval, the proboscis is but just formed, and the tentacles ap- 



Fig. 96. 



Fig. 97. 





pear only as round swellings or knobs. In Fig. 95 a depression 
has taken place at the upper end, presently to be an opening, 
the proboscis is enlarged, and the tentacles lengthened, but still 
turned inward. In Fig. 96 the appendages of the proboscis are 
quite conspicuous, the tentacles are turned outward, and the 



Figs. 94, 95, 96. Medusae buds of Fig 93, in different degrees of development. 
Fig. 97. Young Medusa just freed from the Hydroid ; magnified. 



72 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Jelly-fish is almost ready to break from its attachment, having 
assumed its ultimate outline. Fig. 97 represents it just after it 
has separated from the stem, when it has only two tentacles at 
each cluster and simple knobs around the mouth, instead of the 
complicated branching tentacles of the adult. 

Tubularia. ( Tubularia Couihouyi AG.) 

There are several other Tubularians common in our waters 
which should not be passed over without mention, although as 
this little book is by no means intended as a complete text-book, 
but rather as a volume of hints for amateur collectors, we would 
avoid as much as possible encumbering it with many names, or 
with descriptions already given in more comprehensive works. 
This Tubularia is interesting, however, from the fact that the 
Medusae buds are never freed from the stem, and do not develop 

Fig. 98. Fig. 99. 





into full-grown Jelly-fishes, but always remain abortive. Fig. 98 
represents one head of such a Hydroid with the Medusas buds 
pendent from it in a thick cluster, while in Fig. 99 we have a 
few of them sufficiently magnified to show that, though present 
ing the four chymiferous tubes, they are otherwise exceedingly 
simple in structure, as compared with the free Jelly-fishes. 



Fig. 98. Tubularia ; magnified. 

Fig. 99. Part of cluster of Medusas of Fig. 98 ; magnified. (Ayassiz.) 



HYDRACTINIA. 



73 



(Hydractinia polyclina AG.) 

This is another Tubularian, covering the surface of rocks in 
tide-pools, or attaching itself upon shells inhabited by hermit 
crabs. Indeed it was upon these shells that the Hydractinia was 
first noticed, and it was long supposed that the wanderings to 
which the little colony was thus subjected were necessary for its 
healthy development. But subsequent observations have shown 
that it attaches itself quite as frequently to the solid rock as to 
these nomadic shells. It has a rosy color, and, being very small, 
it looks, until one examines it closely, more like a thick red car 
pet of soft moss, than like a colony of animals. These communi 
ties are distinct in sex, the fertile individuals in each being either 
all male or all female. In Fig. 100 we have a portion of a fe 
male colony, representing one fertile head, in which the buds are 
crowded with Medusas ; one sterile head, surrounded by its 



Fig. 100. 



Fig. 101. 





wreath of tentacles ; and still another member of the society 
whose office is not fully understood, unless it be that of a kind 
of purveyor, catching food for the rest. Fig. 101 represents the 
corresponding individuals taken from a male colony. The sex 
makes little difference in the appearance of the reproductive 
heads. All the individuals of a Hydractinia colony are con 
nected at the base by a horny network, rising occasionally 

Fig. 100. Female colony of Hydractinia ; a sterile individual, b fertile individual producing female 
Medusae, c fertile individual with globular tentacles without Medusae, d efg h i Medusae in different 
stages of growth, o mouth tentacles. (Ayassiz.") 

Fig. 101. Male colony ; a a sterile individuals, b fertile individuals producing male Medusas, d ; 
o globular tentacles, t slender tentacles of sterile individual. (Ayassiz.) 
10 



74 MARINE ANIMALS OF MASSACHUSETTS BAY. 

into points of a conical or cylindrical shape. This polymorphism 
among the Tubularians is another evidence of the relation be 
tween the Siphonophorae, or floating Hydroids, and the fixed 
Hydroids. 



Hybocodon. (Hybocodon prolifer AG.) 

Among our Medusae derived from a Tubularian stock is the 
Hybocodon, viz. the hunchbacked Medusa (Fig. 102), a singular 
little Jelly-fish, odd and unsymmetrical in shape, as its name 
indicates, and interesting from its relations to one of our floating 
communities, the Nanomia, presently to be described. Instead 
of the evenly proportioned bell of the ordinary Medusas, the 
Hybocodon has a one-sided outline (Fig. 102), one large tentacle 
only being fully developed, while the others remain always abor 
tive, so that the whole weight of the structure is thrown on one 
half of the bell. Upon this large tentacle small Jelly-fishes, 
similar to the original, are produced by budding, this process 



Fig. 102. 



Fig. 103. 






going on till ten or twelve such Jelly-fishes (Fig. 103) may be 

seen suspended from the tentacle. Up to this time it has re- 
Fig. 102. Unsymmetrical free Medusa of Hybocodon ; ro chymiferous tubes, v proboscis, s circular 

tube, m young Medusae at base of long tentacle t. (Ayassiz.) 

Fig. 103. Medusa bud of Hybocodon ; a base of attachment, o proboscis, c circular tube, d young 

Medusae at base of long tentacle t. (rfyassiz.) 

Fig. 104. Single head of Hybocodon Hydroid ; a stem, d Medusae buds, o tentacles round mouth. 

(Agassiz.) 



DYSMORPHOSA. 75 

i 

mained connected with the Hydroid from which it arises, a rather 
large Tubularian, usually growing singly (Fig. 104), and of a 
deep orange-red in color. But at this stage of its existence it 
frees itself, and leads an independent life hereafter, swimming 
about with a quick, darting motion. In the account of the Na- 
nomia, the homology between its scale, or abortive Medusa, and 
the Hybocodon, is traced in detail, and I need only allude to it 
here. Though this Medusa is so peculiar in appearance, the 
Tubularian from which it is derived is very like the Tubularia 
Coutlwuyi, already described. This is one of the instances before 
alluded to, in which closely allied forms give rise to very dissimi 
lar ones, or, as in many cases, the very reverse of this takes place, 
and closely allied forms arise from very dissimilar ones. 

Dysmorphosa. (Dysmorphosa fulgurans A. AG.) 

Besides the budding at the base of the tentacle, as in Hyboco 
don, we find another mode of development among Hydroid Me 
dusae, viz. that of budding from the proboscis. One of our most 
common little Jelly-fishes, the Dysmorphosa (Fig. 105), to which 
we owe the occasional blue phosphorescence of the sea, so brilliant 
at times, buds in this manner. Fig. 105 represents an adult Dys- 

Fig. 105. Fig. 106. 





morphosa, on the proboscis of which may be seen three small buds 
in different stages of development. In Fig. 106 the proboscis is 
more enlarged, showing one of the little Jelly-fishes similar to 
the parent, just ready to drop off. We need not wonder at the 

Fig. 105. Dysmorphosa seen in profile ; magnified. 

Fig 106. Magnified proboscis of Dysmorphosa with young Medusae budding from it. 



76 MARINE ANIMALS OF MASSACHUSETTS BAY. 

immense number of these animals, with which the .sea actually 
swarms at times, when we know that as fast as they are 
dropped, and it takes but a few days to complete their de 
velopment, they each begin the same process ; so that in the 
course of a week or ten days one such Medusa, supposing it to 
have produced six buds only, will have given rise to forty-two 
Jelly-fishes, thirty-six of which may be equally prolific in the 
same short period. These Medusa3 budding thus, and swimming 
about, carrying their young with them, bear such a close resem 
blance to the floating communities of Hydroids formerly known as 
Siphonophoras, that did we not know that some of them arise 
from Tubularians, it would be natural to associate them with 
the Siphonophora3. 

Nanomia. (Nanomia cam A. AG.) 

The Nanomia (Fig. 115), our free floating Hydroid, consists, 
when first formed, of a single Hydra containing an oblong oil 
bubble (Fig. 107). The whole organization of such a Hydra is 

limited to a simple digestive cav 
ity ; it has, in fact, but one organ, 
and one function, and consists of 
an alimentary sac resembling the 
probdscis of a Medusa (Fig. 107) ; 
the oil bubble is separated from 
it by a transverse partition, and 
has no connection with the cavity. 
Presently, between the oil bubble 
and the cavity arise a number of 
buds of various character (Fig. 108), which we will describe one 
by one, beginning with those nearest the oil bubble, since these 
upper members of the little swimming community bear a very im 
portant part in its history. The infant community (Fig. 108) 
passes rapidly into the stage represented in Fig. 109, and then 
through all the stages intermediate between this and the adult, 
shown in its natural size in Fig. 115. The upper buds en- 

Fig. 107. Young Nanomia ; magnified. 

Fig. 108. Young Nanomia with rudimentary Medusas. 





NANOMIA. 



77 



large gradually, and soon take upon themselves a perfect Me 
dusa structure (Fig. 110), with the exception of the proboscis, 
the absence of which is easily understood, when we find that 
these Medusae serve the purpose of locomotion only, having no 



Fig. 109. 




Fig. 1JO. 




share in the function of feeding the community, so that a diges 
tive apparatus would be quite superfluous for them. In every 
other respect they are perfect Medusae, attached to the Hydra as 
the Medusa buds always are when first formed, having the (four) 
chymiferous tubes, characteristic of all Hydroid Medusae, radi 
ating from the centre to the periphery ; two of these tubes 
are very winding, as may be seen in Fig. 110, while the other 
pair are straight. The Medusae themselves are heart-shaped 
in form, depressed at the centre of the upper surface, and 
bulging on either side into wing-like expansions, where they 
join the stem. These expansions interlock with one another, 
crossing nearly at right angles. The Medusae-like buds are the 
swimming bells ; by their contractions, alternately taking in and 
throwing out the water, they impel the whole community for 
ward, so that it seems rather to move like one animal, than like 
a combination of individuals. 

Fig. 109. Young Nanomia, older than Fig. 103. 

Fig. 110. Heart-shaped swimming bell of Nanomia ; magnified. 



78 MARINE ANIMALS OF MASSACHUSETTS BAT. 

Besides these locomotive members, the community contains three 
kinds of Hydrae arising as buds from the primitive Hydra below 
the swimming bells, the latter remaining always nearest the oil 
bubble at the top, while the first Hydra, the founder of the com 
munity, in proportion as the new individuals are added, is gradu 
ally pushed downward, and remains always at the end of the 
string, the stem of which is formed by the elongated neck of the 
primitive Hydra. All the three sets of Hydrae have certain fea 
tures in common, while they have other distinguishing character 
istics marking them as distinct individuals. They are all accom 
panied by triangular shields (Fig. Ill), arising with them at the 
Fig U1 same point on the parent stem, and all 

are furnished with tentacles hanging 
down from the summit of the Hydra at 
the side opposite the shield. These facts 
are important to remember, since we 
shall presently perceive, upon analyzing 
their parts, that these Hydras have a close 
homology to the Hybocodon. The ten 
tacles differ in structure as well as in 
number for each kind of Hydra. Hav 
ing shown in what characters they 
agree, let us now take each set individ 
ually, and see what differences they 
present. 

In the first set which we will exam 
ine the Hydra is open-mouthed. Like 
the original Hydra, it is only a digestive 
tube, similar in all respects to the proboscis of a Medusa-disk. 
Its only function is that of feeding, and it shows a laudable fidel 
ity to its calling, being very constantly and earnestly engaged in 
the work. Let us add, however, that in this instance the occu 
pation is not a wholly selfish one, since the cavity of every Hydra 
communicates with that of the stem, and the food taken in at 
these ever-gaping mouths, is at once circulated through all parts 
of the community, with the exception of the oil bubble, from 
which it is excluded by the transverse partition dividing it from 

Fig. 111. Cluster of Medusae with tentacles having pendant knobs. 




NANOMIA. 79 

all the lower members of the stock. The shields share in this 
general nourishment of the compound body by means of chymif- 
erous tubes extending toward the outer surface, and opening into 
the cavity of the stem. The mouth of this Hydra is very flexible 
(Fig. Ill), expanding and contracting at the will of the animal, 
and sometimes acting as a sucker, fastening itself, leech-like, on 
the object from which it seeks to draw its sustenance. (See Fig. 
111.) The tentacles attached to this set of Hydrae are exceed 
ingly long and delicate. They arise in a cluster at the upper 
and inner edge of the Hydra, just at its point of juncture with 
the stem, and being extremely flexible and contractile, their 
long tendril-like sprays are thrown out in an endless variety of 
attitudes. (See Fig. 115.) Along the whole length of this 
kind of tentacle are attached little pendent knobs at even 
distances ; Fig. 112 represents such a knob greatly magnified, 

Fig. 112. Fig. 113. 





and absolutely paved with lasso-cells, the inner and smaller ones 
being surrounded by a row of larger ones. 

The second set of Hydrae (Fig. 113), are also open-mouthed, 
corresponding with those described above, in everything except 
the tentacles, which are both shorter and thicker, and are coiled 
in a corkscrew-like spiral. These are thickly studded for their 
whole length with lasso-cells. (See Fig. 113.) 

In the third and last set of Hydras (Fig. 114), the mouth 

Fig. 112. Magnified pendent knob. 

Fig. 113. Medusa with corkscrew-shaped tentacles. 



80 MARINE ANIMALS OF MASSACHUSETTS BAY. 

is closed ; they have, therefore, no share in feeding the com 
munity, but receive their nourishment from the cavity of the stem 
into which they open. They differ also from the others in having 
a single tentacle instead of a cluster, and on this tentacle the lasso- 
rig. iu. ce ^ s are scattered at uneven distances (Fig. 114). 
The special function of these closed Hydras is yet to 
be explained ; they have oil bubbles at their upper 
end (see Fig. Ill, the top Hydra), and though we 
have never seen them drop off, it seems natural to 
suppose that they do separate from the parent stock, 
and found new communities similar to those from 
which they arise. 

The intricate story of this singular compound ex 
istence does not end here. There is still another set 
of individuals whose share in maintaining the life of 
the community is by no means the least important. 
Little bunches of buds, of a different character from 
any described above, may be seen at certain distances 
along the lower part of the stem. These are the reproductive 
individuals. They are clusters of imperfect sexual Medusae, re 
sembling the rudimentary Medusa3 of Tubularia (Fig. 99), which 
are never freed from the parent stem, but discharge their contents 
at the breeding season. Like many other compound Hydroids, 
the sexes are never combined, in one of these communities ; they 
are always either male or female, and as those with female buds 
have not yet been observed, we can only judge by inference of 
their probable character. From what is already known, how 
ever, of Hydroid communities of a like description, we suppose 
that the process of reproduction must be the same in these, and 
that the female stocks of Nanomia give birth to small Jelly- 
fishes, the eggs of which become oil bubbles, similar to that with 
which our little community began. (Fig. 108.) 

By the time all these individuals have been added along the 
length of the stem, the stem itself has grown to be about three 
inches long (Fig. 115), though the tentacles hanging from the 
various members of the community give to the whole an appear 
ance of much greater length. The motion of this little string of 

Fig. 114. Medusa with a simple thread-like tentacle. 



NANOMIA. 



81 



living beings is most graceful. The oil bubble (Fig. 116) at the 
upper end is their float ; the swimming bells immediately below 
it (Fig. 110), by the convulsive contractions of which they move 
along, are their oars. The water is not taken in and expelled 



Fig. 115 




again by all the bells at once, but first from all the bells on 
one side, beginning at the lower one, and then from all those on 
the opposite side, beginning also at the lower one ; this alter- 



Fig. 115. Adult Nanoraia, natural size, at rest. 
11 




82 MARINE ANIMALS OF MASSACHUSETTS BAY. 

nate action gives to their movements a swinging, swaying charac 
ter, expressive of the utmost freedom and grace. Whether such 
rig. lie. a little community darts with a lightning-like speed 
through the water, or floats quietly up and down, 
for its movements are both rapid and gentle, it 
always sways in this way from side to side. Its 
beauty is increased by the spots of bright red 
scattered along the length of the stock at the 
base and tips of the Hydra?, as well as upon the 
tentacles. The movements and attitudes of the 
tentacles are most various. Sometimes they 
shoot them out in straight lines on either side, and then the 
aspect of the whole thing reminds one of a tiny chandelier in 
which the coral drops make the pendants, or they may be caught 
up in a succession of loops or floating in long streamers ; indeed, 
there is no end to the fantastic forms they assume, ever astonish 
ing you by some new combination of curves. The prevailing 
hue of the whole community is rosy, with the exception of the 
oil bubble or float, which looks a bright garnet color when seen 
in certain lights. 

Let us now compare one of the Hydras hanging from the stem 
(Fig. 113) with the Hybocodon (Fig. 102). The reader will 
remember the unsymmetrical bell of this singular Medusa, one 
half of its disk more largely developed than the other, with the 
proboscis hanging from the centre, and the cluster of tentacles 
from one side. Let us now split the bell so as to divide it in two 
halves with the proboscis hanging between them ; next enlarge the 
side where there are no tentacles, and give it a triangular out 
line ; then contract the opposite side so as to draw up the cluster 
of tentacles to meet the base of the proboscis, and what have we ? 
The proboscis now corresponds to the Hydra of our Nanomia, 
with the cluster of tentacles attached to its upper edge (Fig. 
113), while the enlarged half of the bell represents the shield. 
If this homology be correct it shows that the Nanomia is not, as 
some naturalists have supposed all the Siphonophores to be, a 
single animal, its different parts being a mere collection of organs 
endowed with special functions, as feeding, locomotion, repro- 

Fig. 116. Oil float of Nanomia ; greatly magnified. 



PHYSALIA. 



83 



Fig. 117. 



duction, &c., but that it is indeed a community of distinct indi 
viduals corresponding exactly to the polymorphous Hydroids, 
whose stocks are attached, such as Hydractinia, and differing from 
them only in being free and floating. 

The homologies of the Siphonophoras or floating Hydroids, 
with many of the fixed Hydroids, is perhaps more striking 
when we compare the earlier stages of 
their growth. Suppose, for instance, that 
the planula of our Melicertum (See Fig. 
81) should undergo its development with 
out becoming attached to the ground, 
what should we then have ? A floating 
community (Fig. 83), including on the 
same stock like the Nanomia, both sterile 
and fertile Hydrae, from the latter of which 
Medusae bells are developed. The little 
Hydractinia community (Fig. 100), in 
which we have no less than four distinct 
kinds of individuals, each performing a 
definite distinct function, affords a still 
better comparison. 

Physalia. (Physalia Arethusa TIL.) 

Among the most beautiful of the Sipho- 
nophores, is the well-known Physalia or 
Portuguese man-of-war, represented in Fig. 
117). The float above is a sort of crested 
sac or bladder, while the long streamers 
below consist of a number of individuals 
corresponding in their nature and functions to those composing a 
Hydroid community. Among them are the fertile and sterile 
Hydras (Fig. 118), the feeders and Medusas bells (Fig. 119). 
The Physalia properly belongs to tropical waters, but sometimes 
floats northward, in the warm current of the Gulf Stream, and 
is stranded on Cape Cod. When found so far from their home, 
however, they have usually lost much of their vividness of color ; 




Tig. 117. Physalia ; ab air sac with crest c, m bunches of individuals, n central tentacles, 1 1 ex 
panded tentacles. (Agassiz.) 



84 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



to judge of their beauty one should see them in the Gulf of Mex 
ico, sailing along with their brilliant float fully expanded, their 
crest raised, and their long tentacles trailing after them. 



Fig. 118. 




Fig. 119. 




Velella. ( VeUla mutica Bosc.) 

Another very beautiful floating Hydroid, occasionally caught 
in our waters, though its home is also far to the south, is the 



Fig. 120. 



Fig. 121. 





Velella (Fig. 120). It is bright blue in color, and in form 1101 
unlike a little flat boat with an upright sail. Its Medusa 
(Fig. 121) resembles so much that of some of our Tubu- 
larians, that it has actually been removed on this account from 
the old group of Siphonophorae, and placed next the Tubula- 
rians ; another evidence of the close affinity between the former 
and the Hydro-ids. 

Fig. 118. Bunch of Hydrse ; a base of attachment, bb b single Hydrae, c c tentacles. (Agassiz.) 

Fig. 119. Bunch of Hydrae ; cluster of Medusae ; b b Hydrae with tentacles, c d bunches of Medusae. 
(Ayassiz.) 

Fig. 120. Velella ; m so-called mouth, a tentacles. (Agassiz.) 

Fig. 121. Free Medusae of Velella ; a proboscis, U chymiferous tube, c circular tube. (Ayassiz.) 



MODE OF CATCIIIX3 JELLY-FISHES. 85 



MODE OF CATCHING JELLY-FISHES. 

NOT the least attractive feature in the study of these animals, 
is the mode of catching them. We will suppose it to be a warm, 
still morning at Nahant, in the last week of August, with a 
breath of autumn in the haze, that softens the outlines of the op 
posite shore, and makes the horizon line a little dim. It is about 
eleven o clock, for few of the Jelly-fishes are early risers; they like 
the warm sun, and at an earlier hour they are not to be found 
very near the surface. The sea is white and glassy, with a slight 
swell but no ripple, and seems almost motionless as we put off in 
a dory from the beach near Saunders s Ledge. We are provided 
with two buckets, one for the larger Jelly-fishes, the Zygodactyia, 
Aurelia, &c., the other for the smaller fry, such as the various 
kinds of Ctenpphorae, the Tima, Melicertum, <fec. Beside these, 
we have two nets and glass bowls, in which to take up the more 
fragile creatures that cannot bear rough handling. A bump or 
two on the stones before we are fairly launched, a shove of the 
oar to keep the boat well out from the rocks along which we 
skirt for a moment, and now we are off. We pull around the 
point to our left and turn toward the Ledge, filling our buckets 
as we go. Now we are crossing the shallows that make the 
channel between the inner and outer rocks of Saunders s Ledge. 
Look down, how clear the water is and how lovely the sea 
weeds, above which we are floating, dark brown and purple 
fronds of the Ulvae, and the long blades of the Laminaria with 
mossy green tufts between. As we issue from this narrow pas 
sage we must be on the watch, for the tide is rising, and may 
come laden with treasures, as it sweeps through it. A sudden 
cry from the oarsman at the bow, not of rocks or breakers 
ahead, but of "A new Jelly-fish astern! " The quick eye of the 
naturalist of the party pronounces it unknown to zoologists, un- 
described by any scientific pen. Now what excitement ! " Out 
with the net ! we have passed him ! he has gone down ! no, 
there he is again ! back us a bit." Here he is floating close by 
us ; now he is within the circle of the net, but he is too delicate 



86 MARINE ANIMALS OF MASSACHUSETTS BAY. 

to be caught safely in that way, so, while one of us moves the 
net gently about, to keep him within the space enclosed by it, 
another slips the glass bowl under him, lifts it quickly, and there 
is a general exclamation of triumph and delight, we have him. 
And now we look more closely ; yes, decidedly he is a novelty as 
well as a beauty. (See Fig. 122, Ptychogena lactea A. Ag.) Those 

Fig. 122. 




white mossy tufts for ovaries are unlike anything we have found 
before (Fig. 123), and not represented in any published figures 
of Jelly-fishes. We float about here for a while, hoping to find 
more of the same kind, but no others make their appearance, 
and we keep on our way to East Point, where there is a capital 
fishing ground for Medusae of all sorts. Here two currents meet, 
and the Jelly-fishes are stranded as it were along the line of 
juncture, able to move neither one way nor the other. At this 
spot the sea actually swarms with life ; one cannot dip the net 
into the water without bringing up Pleurobrachia, Bolina, Idyia, 
Melicertum, <fec., while the larger Zygodactyla and Aurelia float 
about the boat in numbers. These large Jelly-fishes produce a 
singular effect as one sees them at some depth beneath the water ; 

Fig. 122. Ptychogena, natural size. 



MODE OF CATCHING JELLY-FISHES. 87 

the Aurelise, especially, with their large white disks, look like 
pale phantoms wandering about far below the surface ; but they 
constantly float upward, and if not too far out of reach, one may 
bring them up by stirring the water under them with the end of 
the oar. 

When we have passed an hour or so floating about just 
beyond East Point, and have nearly 
filled our buckets with Jelly-fishes of 
all sizes and descriptions, we turn 
and row homeward. The buckets 
look very pretty as they stand in the 
bottom of the boat with the sun 
shine lighting up their living con 
tents. The Idyia glitters and spar 
kles with ever-changing hues, the 
Pleurobrachiae dart about, trailing 
their long graceful tentacles after 
them, the golden Melicerta are kept 
in constant motion by their quick, 
sudden contractions, and the deli 
cate transparent Tima floats among 
them all, not the less beautiful be 
cause so colorless. There is an un 
fortunate Idyia, who, by some mis 
take, has got into the wrong bucket 
with the larger Jelly-fish, where a Zy- 
godactyla has entangled it among his tentacles and is quietly 
breakfasting upon it. 

During our row the tide has been rising, and as we near the 
channel of Saunders s Ledge, it is running through more strongly 
than before, and at the entrance of the shallows a pleasant sur 
prise is prepared for us ; no less than half a dozen of our new 
friends (the Ptychogena as he has been baptized), come to look 
for their lost companion perhaps, await us there, and are pres 
ently added to our spoils. We reach the shore heavily laden 
with the fruits of our morning s excursion. 

The most interesting part of the work for the naturalist is 

Fig. 123. Ovary of Ptychogena 5 magnified. 




88 MARINE ANIMALS OF MASSACHUSETTS BAY. 

still to come. On our return to the Laboratory, the contents of 
the buckets are poured into separate glass bowls and jars ; hold 
ing them up against the light, we can see which are our best 
and rarest specimens ; these we dip out in glass cups and place 
by themselves. If any small specimens are swimming about at 
the bottom of the jar, and refuse to come within our reach, there 
is a very simple mode of catching them. Dip a glass tube into the 
water, keeping the upper end closed with your finger, and sink it 
till the lower end is just above the animal you want to entrap ; 
then lift your finger, and as the air rushes out the water rushes 
in, bringing with it the little creature you are trying to catch. 
When the specimens are well assorted, the microscope is taken 
out, and the rest of the day is spent in studying the new Jelly- 
fishes, recording the results, making notes, drawings, <fec. 

Still more attractive than the rows by day are the night ex 
peditions in search of Jelly-fishes. For this object we must 
choose a quiet night, for they will not come to the surface if the 
water is troubled ; Nature has her culminating hours, and she 
brings us now and then a day or night on which she seems to have 
lavished all her treasures. It was on such a rare evening, at the 
close of the summer of 1882, that we rowed over the same course 
by Saundcrs s Ledge and East Point described above. .The 
August moon was at her full, the sky was without a cloud, and 
we floated on a silver sea ; pale streamers of the aurora quivered 
in the north, and notwithstanding the brilliancy of the moon, they 
too cast their faint reflection in the ocean. We rowed quietly 
along past the Ledge, past Castle Rock, the still surface of the 
water unbroken, except by the dip of the oars and the ripple of 
the boat, till we reached the line off East Point, where the Jelly- 
fishes are always most abundant, if they are to be found at all. 
Now dip the net into the water. What genie under the sea has 
wrought this wonderful change ? Our dirty, torn old net is sud 
denly turned to a web of gold, and as we lift it from the water 
heavy rills of molten metal seem to flow down its sides and col 
lect in a glowing mass at the bottom. The truth is, the Jelly- 
fishes, so sparkling and brilliant in the sunshine, have a still love 
lier light of their own at night ; they give out a greenish golden 
light as brilliant as that of the brightest glow-worm, and on a 



MODE OF CATCHING JELLY-FISHES. 89 

calm summer night, at the spawning season, when they come to 
the surface in swarms, if you do but dip your hand into the 
water it breaks into sparkling drops beneath your touch. There 
are no more beautiful phosphorescent animals in the sea than 
the Medusae ; it would seem that the expression, " rills of molten 
metal " could hardly apply to anything so impalpable as a Jelly 
fish, but, although so delicate in structure, their gelatinous disks 
give them a weight and substance ; and at night, when their 
transparency is not perceived, and their whole mass is aglow with 
phosphorescent light, they truly have an appearance of solidity 
which is most striking, when they are lifted out of the water and 
flow down the sides of the net. 

The various kinds present very different aspects ; wherever 
the larger Atirelise and Zygodactyla3 float to the surface, they 
bring with them a dim spreading halo of light, the smaller 
Ctenophorae become little shining spheres, while a thousand 
lesser creatures add their tiny lamps to the illumination of 
the ocean ; for this so-called phosphorescence of the sea is by 
no means due to the Jelly-fishes alone, but is also produced 
by many other animals, differing in the color as well as the in 
tensity of their light, and it is a curious fact that they seem 
to take possession of the field by turns. You may row over the 
same course, which a few nights since glowed with a greenish 
golden light wherever the surface of the water was disturbed, and 
though equally brilliant, the phosphorescence has now a pure 
white light. On such an evening, be quite sure that when you 
empty your buckets on your return and examine their contents 
you will find that the larger part of your treasures are small 
Crustacea (little shrimps). Of course there will be other phos 
phorescent creatures, Jelly-fishes, <fec., among them, but the pre- 
dominant color is given by these little Crustacea. On another 
evening the light will have a bluish tint, and then the phosphores 
cence is principally due to the Dysmorphosa (Fig. 105). 

Notwithstanding the beauty of a moonlight row, if you would 
see the phosphorescence to greatest advantage you must choose a 
dark night, when the motion of your boat sets the sea on fire 
around you, and a long undulating wave of light rolls off from 
your oar as you lift it from the water. On a brilliant evening 

12 



90 MARINE ANIMALS OF MASSACHUSETTS BAY. 

this effect is lost in a great degree, and it is not until you dip 
your net fairly under the moonlit surface of the sea, that you 
are aware how full of life it is. Occasionally one is tempted out 
by the brilliancy of the phosphorescence, when the clouds are so 
thick that water, sky, and land become one indiscriminate mass 
of black, and the line of rocks can be discerned only by the vivid 
flash of greenish golden light, when the breakers dash against 
them. At such times there is something wild and weird in the 
whole scene, which at once fascinates and appalls the imagination ; 
one seems to be rocking above a volcano, for the surface around 
is intensely black, except where fitful flashes or broad waves of 
light break from the water under the motion of the boat or the 
stroke of the oars. It was on a night like this, when the phos 
phorescence was unusually brilliant, and the sea as black as ink, 
the surf breaking heavily and girdling the rocky shore with a wall 
of fire, that our collector was so fortunate as to find in the rich 
harvest he brought home the entirely new and exceedingly pretty 
little floating Hydroid, described under the name of Nanomia 
(Fig. 115). It was in its very infancy (Fig. 108), a mere bub 
ble, not yet possessed of the various appendages which eventually 
make up its complex structure ; but it was nevertheless very im 
portant to have seen it in this early stage of its existence, since, 
when a few full-grown specimens were found in the autumn, 
which lived for some days in confinement and quietly allowed 
their portraits to be taken (see Fig. 115), it was easy to connect 
the adult animal with its younger phase of life and thus make a 
complete history. 

Marine phosphorescence is no new topic, and we have dwelt too 
long, perhaps, upon a phenomenon that every voyager has seen, 
and many have described ; but its effect is very different, when 
seen from the deck of a vessel, from its appearance as one floats 
through its midst, distinguishing the very creatures that produce 
it, and any account of the Medusae which did not include this 
most characteristic feature would be incomplete. 



ECHINODERMS. 

/ . 

Library* 

ECHINODERMS. V 9 

t California. 

^Sfcr .. ,. . 

OUR illustrations and descriptions of Ecliinoderms are scanty 
in comparison to those of the preceding class ; for while, in con 
sequence, perhaps, of the combined influence of the Gulf Stream 
and the cold arctic current on the New England shore, Acalephs 
are largely represented in our waters, our marine fauna is 
meagre in Ecliinoderms. But although we have few varieties, 
those which do establish themselves on a coast seemingly so 
ungenial for others of their kind, such as the Echinus, and our 
common Star-fish, for instance, thrive well and are very abun 
dant. The class of Ecliinoderms includes five orders, viz. CRI- 
NOIDS, OPHIURANS, STAR-FISHES, SEA-URCHINS, and HOLOTHURIANS. 
The animals composing these orders differ so widely in appear 
ance that it was very long before their true relations were de 
tected, and it was seen that all their external differences were 
united under a common plan. Let us compare, for instance, the 
worm-like Holothurians (Figs. 124, 126, 127) with all the host of 
Star-fishes (Figs. 142, 146, 147) and Sea-urchins (Figs. 131, 139), 
or compare the radiating form of the Star-fish, its arms spreading 
in every direction, with the close spherical outline of the Sea- 
urchin, or the Crinoid floating at the end of a stem (Fig. 152) 
with either of these, and we shall cease to wonder that naturalists 
failed to find at once a unity of idea under all these varieties of 
execution. And yet the fundamental structure of the class of 
Ecliinoderms is represented as distinctly by any one of its five 
orders as by any other, and is absolutely identical in all. They 
differ only by trifling modifications of development. 

In Ecliinoderms as a class, the body presents three regions dif 
fering in structure, and on the greater or less development of 
these regions or systems, as we may call them, their chief differen 
ces are based. Take, for instance, the dorsal system, the nature 
of which is explained by the name, indicating of course the back 
of the animal, though it does not necessarily imply the upper 
side of the body, since some of the Ecliinoderms, as the stemmed 
Crinoids, for example, carry the dorsal side downward, while 



92 MARINE ANIMALS OF MASSACHUSETTS BAY. 

the Star-fishes and Sea-urchins carry it upward, and. the Holothu- 
rians, moving with the mouth forward, have the dorsal system 
at the opposite end of the body. Whatever the natural attitude 
of the animal, however, and the consequent position of the dorsal 
region, it exists alike in all the five orders, though it has not the 
same extent and importance in each. But in all it is made up of 
similar parts, bears the same relation to the rest of the body, has 
the same share in the general economy of the animal. And 
though when we compare the spreading back of a Star -fish with 
the small area on the top of a Sea-urchin, where all the zones 
unite, we may not at once see the correspondence between them, 
yet a careful comparison of all their structural details shows that 
they are both built with the same elements and represent the 
same region, though it is stretched to the utmost in the one case, 
and greatly contracted in the other. 

This being true of the dorsal system, let us look at another 
equally important structural feature in this class. All Echino- 
derms have locomotive organs peculiar to themselves, a kind 
of suckers which may be more or less numerous, larger or 
smaller, in different species, but are always appendages of the 
same character. These are variously distributed over the body, 
but always with a certain regularity occupying definite spaces, 
shown by investigation to be homologous in all. For instance, 
the rays of the Star-fish correspond in every detail on their under 
side, along which the locomotive suckers run, with the zones on 
the Sea-urchin, from end to end of which the suckers are ar 
ranged ; and the same is equally true of the distribution of the 
suckers on the Holothurians, Ophiurans, and Crinoids, though, 
as most persons are less familiar with these orders than with 
the other two, it might not be so easy to point out the coin 
cidence to our readers. These suckers are called the ambu 
lacra, the lines along which they run are called the ambulacral 
rows or zones, while the system of locomotion as a whole is 
known as the ambulacral system. Since these organs are thus 
regularly distributed over the body in distinct zones or rows, it 
follows that the latter must be divided by intervening spaces. 
These intervals are called the interambulacral spaces ; but while 
in some orders they are occupied by larger plates and prominent 



ECHINODERMS. 93 

spines, as in the Sea-urchin and Star-fish, in others they are either 
comparatively insignificant or completely suppressed, as in the 
Crinoids and Ophiurans. Such are the three regions or systems 
which by their greater or less development introduce an almost 
infinite variety of combinations into this highest class of Radi 
ates. It may not be amiss before proceeding further to compare 
the five orders with reference to this point, and see which of 
these three systems has the preponderance in each one. 

Taking the orders in their rank and beginning with the lowest, 
we find in the Crinoids that the dorsal system preponderates, 
being composed of highly complicated plates, and developed to 
such a degree as to form in many instances a stem by which the 
animal is attached to the ground, while the ambulacral system is 
limited to a comparatively small area, and the interanibulacral 
system is wanting. The order of Crinoids has diminished so 
much in modern geological times that we must consult its 
fossil forms in order to understand fully the peculiar adaptation 
of the Echinoderm plan in this group. 

In the Ophiurans, the dorsal system is still large, and though 
it no longer stretches out to form a stem, it folds over on the un 
der side of the animal so as to enclose entirely the ambulacral 
system, forming a kind of shield for the arms. Here also the in 
teranibulacral system is wanting. 

In the Star-fishes the dorsal system encroaches less upon the 
structure of the animal. The back and oral side here correspond 
exactly in size, and though the flat leathery upper surface of 
the animal, covered with spines, serves as a protection to the 
delicate ambulacral suckers which find their way between the 
rows of small plates along the under side of the arms, yet it does 
not enfold them as in the Ophiurans. On the contrary, in the 
Star-fishes the ambulacral rows are protected on either side by a 
row of the so-called interambulacral plates, through which no 
suckers pass. 

In the Sea-urchin, the dorsal system is contracted to a mini 
mum, forming a small area on the top of the animal, the rows of 
interambulacral plates which are separated and lie on either side 
of the ambulacra in the Star-fish being united in the Sea-urchin, 
and both the ambulacral and the interambulacral systems bent 



94 MARINE ANIMALS OF MASSACHUSETTS BAY. 

upward, meeting in the small dorsal area above, so as to form a 
spherical outline. Here the ambulacral and interambulacral 
systems have taken a great preponderance over the dorsal system, 
and the same is the case with the Holothurians, in which the 
same structure is greatly elongated, the dorsal system being 
thus pushed out as it were to the end of a cylinder, while the 
ambulacral and interambulacral systems run along its whole 
length. All Echinoderms without exception have ambulacral 
tubes, even though in some there are no external ambulacral 
suckers connected with them. 

There is one organ peculiar to the class of Echinoderms, the 
general structure of which may be described here, since it is 
common to them all, with the exception of the Crinoids, the 
anatomy of which is, however, so imperfectly understood, that 
we are hardly justified in assuming that it does not exist even 
in that order. This organ is known as the madreporic body ; 
it is a small sieve or limestone filter opening into a tube or 
canal ; by means of this tube, which connects with the am 
bulacral system, the water from without, first filtered through 
the madreporic body and thus freed from any impurities, is con 
veyed to the ambulacra. In the more detailed account of the 
different orders we shall see what is the position of this singular 
organ in each group, and how it is adapted in them all to their 
special structure. The development of Echinoderms forms one 
of the most wonderful chapters in the annals of Natural History. 
Marvellous as is the embryonic history of the Acalephs, including 
all the different aspects they assume in the cycle of their growth, 
it is thrown into the shade by the transformations which Echino 
derms undergo before assuming their adult condition. This 
singular mode of development, although it has features recalling 
the development of Jelly-fishes from Hydroids, is nevertheless 
entirely distinct from it, and is known only in the class of Echi 
noderms. As the whole story is given at length in the chapter 
on the embryology of the Echinoderms, we need only allude to it 
here in general terms. We owe the discovery of this remarkable 
process to Johannes Miiller, one of the greatest anatomists of 
this century. 



HOLOTHURIANS. 



95 




Fig. 124. 



HOLOTHUKIANS. rftr^ 

Synapta. (Synapta tennis AYRES.) 

THIS is one of the most curious of the Holothurians, and easily 
observed on account of its transparency, which allows us to see its 
internal structure. It has a 
long cylindrical body (Fig. 
124) along the length of 
which run the five rows of 
ambulacra, which are in this 
instance closed tubes with 
out any projecting suckers 
or locomotive organs of any 
kind attached to them, so 
that the name is retained 
only on account of their cor 
respondence in position, and 
not from any similarity of 
function to the ambulacra in 
Star-fishes and Sea-urchins. 
But though the ambulacra 
in Synapta are in fact mere 
water-tubes like the vertical 
tubes in the Ctenophorse, by 
means of which the water, 
first filtered through the 
madreporic body, circulates 
along the skin, they are as 
organs perfectly homologous 

with the ambulacra in all other Echinoderms. The mouth has 
a circular tube around the aperture, and a wreath of branching 
tentacles encircling it. The habits of these animals are singular. 
They live in very coarse mud, but they surround themselves with 
a thin envelope of finer sand, which they form by selecting the 

Fig. 124. Synapta, natural size. 




96 MARINE ANIMALS OF MASSACHUSETTS BAY. 

smaller particles with their tentacles, and making a ring around 
their anterior extremity. This ring they then push down along 
the length of the body, and continue this process, adding ring 
after ring, till they have entirely encircled themselves with a 
sand tube. They move the rings down partly by means of con 
tractions of the body, but also by the aid of innumerable append 
ages over the whole surface. To the naked eye these appendages 
appear like little specks on the skin ; but under the microscope 
they are seen to be warts projecting from the surface, each one 
containing a little anchor with the arms turned upward (Fig. 
125). Around the mouth these warts are larger, but do not 
contain any anchors. It will be seen here 
after that these appendages are homologous 
with certain organs in other Holothurians, 
the warts with the anchors correspond 
ing to the limestone pavement covering 
or partially covering the surface of the 
Cuvieria, for instance, while those without 
anchors correspond to the so-called false 
ambulacra in Pentacta. By means of these 
appendages, though aided also by the con 
tractions of the body, the Synaptae move 
through the mud and collect around them 
selves the sand tube in which they are en 
cased. Their food is very coarse for animals so delicate in struc 
ture. When completely empty of food they are white, perfectly 
transparent, and the spiral tube forming the digestive cavity may 
be seen wound up and hanging loosely in the centre for the whole 
length of the body. In such a condition it is of a pale yellow 
color. But look at one that is gorged with food. The whole 
length of the alimentary canal is then crowded with sand, peb 
bles, and shells, distinctly seen through the transparent skin, and 
giving a dark gray color to the whole body. They swallow the 
sand for the sake of the nutritious substance it contains, and 
having assimilated and digested this, they then eject the harder 
materials. The motion of the body in consequence of its contrac- 

Fig. 125. Anchor of Synapta 5 a anchor, w plate upon which anchor is attached 5 greatly mag- 
niaed. 




CAUDINA. 



97 



tions is much like that of leeches, and on this account these 
Synaptae were long supposed to be a transition type between the 
Radiates and worms. The body grows to a great length, often 
half a yard and more, but constantly drops large portions from 
its posterior part, by means of its own contractions, or breaks it 
self up by the expulsion of the intestines, which are very readily 
cast out. The tentacles are hollow, consisting of a central rib 
with branches from either side. In the Synaptse, as in all the 
Holothurians, the madreporic body is placed near the mouth, 
between two of the ambulacra, and opposite the fifth or odd one. 
The tube, connecting with the central tube around the mouth, 
by means of which it communicates with the ambulacral tubes, 
is very short. 

Caudina. (Cawlina arenata STIMPS.) 

Several other Holothurians are frequently met with on our 
shores. Among them is the Caudina arenata (Fig. 126), a 
small Holothurian, yellowish in color, and thick in texture, 

Fig. 126. 



by no means so pretty as the white transparent Synapta ; the 
tentacles are short, resembling a crown of cloves around the 
mouth. It lives in the sand, and may be found in great numbers 
on the sandy beaches after a storm. 



Fig. 126. Caudina arenata ; natural size. 



13 



98 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Cuvieria. (Cuvieria squamata D. & K.) 

The Holotlmrian of our coast, excelling all the rest in beauty, 
is the Cuvieria. (Fig. 127.) As it lies 011 the sand, a solid red 
lump, with neither grace of form nor beauty of color, even the 
vividness of its tint growing dull and dead when it is removed 
from its native element, certainly no one could suspect that it 
possessed any hidden charm ; but place it in a glass bowl with 
fresh sea-water ; the dull red changes to deep vivid crimson, the 
tentacles creep out (Fig. 127) softly, and slowly, till the mouth 

Fig. 127. 




is surrounded by a spreading wreath, comparable for richness of 
tint, and for delicate tracery, to the most beautiful sea-weeds. 
These tentacles, when fully expanded, are as long as the body it 
self. A limestone pavement composed of numerous pieces covers 
almost the whole surface of the animal ; this apparatus cor 
responds, as we have already mentioned, to the warts containing 
anchors in the Synapta ; but in the latter, the limestone parti 
cles are smaller, whereas in the Cuvieria they are developed to 
a remarkable extent. This animal is very sluggish, the ambula- 
cral suckers, found only on three of the tubes, being arranged 
in such a way as to form a sort of sole on which they creep ; 

Fig. 127. Cuvieria ; natural size. 



PENTACTA. 



99 



the sole is tough and leathery in texture, but free from the 
limestone pavement described above. The young (Figs. 128, 
129) are very common, swimming freely about, and more 
readily found than the adult ; they are of a bright vermilion 
color, but the tentacles hardly branch at that age, nor is the 
limestone pavement formed, which gives such a peculiar aspect 

Fig. 129. 



Fig. 128. 





to the full-grown animal. The young Cuvieria, somewhat older 
than that represented in Fig. 129, are found in plenty under 
stones at low-water mark, just after they have given up their 
nomadic habits, and when the limestone pavement begins to be 
developed. 

Pentacta. (Pentacta frondosa JAG.) 

The highest of our Holothurians in structure, is the Pentacta. 
(Fig. 130.) It is very rare on our beaches, though occasionally 
found under stones at low-water mark ; farther north, in Maine, 
and at Grand Manan, it is very common, covering all the rocks 
near low-water mark. It is a chocolate brown in color, and 



Fig. 128. Young Cuvieria, much enlarged ; I body, g tentacles. 

Fig. 129. Somewhat older Cuvieria ; I body, g tentacle round mouth, g 1 tentacle of sole, b madre- 
poric tentacle. 



100 MARINE ANIMALS OF MASSACHUSETTS BAY. 

measures, when fully expanded, some fifteen to eighteen inches 
in length. Unlike the Cuvieria, the ambulacral suckers are 
evenly distributed and almost equally developed on all the tubes ; 
between the five rows of ambulacral suckers are scattered irregu 
larly certain appendages resembling suckers, but found on exam 
ination not to be true locomotive suckers, and called on that 

Fig. 130. 



account false ambulacra. These are the organs corresponding 
to the warts around the mouth of the Synapta. Although the 
ambulacral suckers are, as we have said, equally developed on all 
the tubes, yet the Pentacta does not use them indiscriminately 
as locomotive organs. In Pentacta, as well as in all Holotlm- 
rians, whether provided with ambulacral suckers, or, like the 
Synapta and Caudina, deprived of them, the odd ambulacrum, 
viz. the one placed opposite the madreporic body, is always used 
to creep upon, and forms the under surface of the animal. 

The correspondence between the different phases of growth in 
the young Pentacta, and the adult forms of the orders described 
above, the Synapta, Caudina, Cuvieria, and Pentacta itself, is a 
striking instance of the way in which embryonic forms illustrate 
the relative standing of adult animals. In the earlier stages of 
its development, the ambulacral tubes alone are developed in the 
Pentacta ; in this condition it recalls the lower orders of Holo- 
thurians, as the Synapta and Caudina ; then a sole is formed by 
the greater development of three of the ambulacra, and in this 
state it reminds us of the next in order, the Cuvieria, while it is 

Fig. 130. Pentacta frondosa ; expanded about one third the natural size. 



ECHINOIDS. 101 

only in assuming its adult form that the Pentacta develops its 
other ambulacra, with their many suckers. 

The Pentacta resembles the Trepang, so highly valued by the 
Chinese as an article of food, and forms a not unsavory dish, 
having somewhat the flavor of lobster. 




Sea-urchin. (Toxopneustes drobachiensis AG.) 

Sea-urchins (Fig. 131) are found in rocky pools, hidden away 
usually in cracks and holes. They like to shelter themselves in 
secluded nooks, and, not satisfied even with the privacy of such a 
retreat, they cover themselves with sea-weed, drawing it down 
with their tentacles, and packing it snugly above them, as if to 
avoid observation. This habit makes them difficult to find, and 
it is only by parting the sea-weed, and prying into the most 
retired corners in such a pool, that one detects them. Their 
motions are slow, and they are less active than either the Star 
fish or the Ophiuran, to both of which they are so closely allied. 

Let us look at one first, as seen from above, with all its various 
organs fully extended. (Fig. 131.) The surface of the animal is 
divided by ten zones, like ribs on a melon, only that these zones 
differ in size, five broad zones alternating with five narrower ones. 
The broad zones, representing the interambulacral system, are 
composed of large plates, supporting a number of hard projecting 
spines, while the narrow zones, forming the ambulacral system, 
are pierced with small holes, arranged in regular rows, (Fig. 132,) 
through which extend the tentacles terminating with little cups 
or suckers. These zones converge towards the summit of the ani 
mal, meeting in the small area which here represents the dorsal 
system ; this area is filled by ten plates, five larger ones at the 
extremity of the interambulacral zones, and five smaller ones at 
the extremity of the ambulacral zones. (Fig. 132.) In the five 
larger plates are the ovarian openings, so called because each 



102 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



one is pierced by a small hole through which the eggs are 
passed out, while in the five smaller plates are the eye-specks. 
The ovaries themselves consist of long pouches or sacs, carried 
along the inner side of each ambulacrum ; one of these ovarian 
plates is larger than the others, and forms the madreporic body, 

?ig. 131. 




being pierced with many minute holes ; here, as in the Star-fish, 
it is placed between two of the ambulacral rows, and opposite the 
fifth or odd one. Looked at from the under or the oral side, as 
seen in Fig. 184, the animal presents the mouth, a circular aper 
ture furnished with five teeth in its centre ; these five teeth open- 
rig. 131. Toxopneustes from above, with all the appendages expanded ; natural size. 



SEA-URCHIN. 



103 



ing into a complicated intestine to be presently described. From 
the month, the ten zones diverge, curving upward to meet in the 
dorsal area on the summit of the body. (Fig. 133.) 

Fig. 132. Fig. 133. 





r --b \ ^^sps&desss 

liilSliiPi 

l^ifil^ 

"fejfts^ 

Let us now examine the appearance and functions of the various 
appendages on the surface. The tentacles have a variety of func 
tions to perform ; they are the locomotive appendages, and for 
this reason, as we have seen, the zones along which they are placed 
are called the ambulacra, while the intervening spaces, or the 
broad zones, are called the interambulacra. It should not be sup 
posed, however, that the locomotive appendages are the only ones 
to be found on the ambulacra, for spines occur 011 the narrow as 
well as on the broad ones, though the larger and more prominent 
ones are always placed on the latter. The tentacles are also 
subservient to circulation, for the water which is taken in at the. 
madreporic body passes into all the tentacles, sometimes called on 
that account water-tubes. Beside these offices the tentacles are 
constantly busy catching any small prey, and conveying it to 
the mouth, or securing the bits of sea-weed with which, as has 
been said, these animals conceal themselves from observation. 
It is curious to see their fine transparent feelers, fastening them 
selves by means of the terminal suckers on such a floating piece 
of sea-weed, drawing it gently down and packing it delicately 
over the surface of the body. As locomotive appendages, the ten 
tacles are chiefly serviceable on the lower or oral side of the ani 
mal, which always moves with the mouth downward. About this 
portion of the body the tentacles are numerous (Fig. 134) and 
large, and when the animal advances it stretches them in a given 



Fig. 132. Portion of shell of Fig. 131, with spines rubbed off. (Ayassiz.) 
Fig. 133. Sea-urchiu shell with all the spines removed. (Agassiz.) 



104 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



direction, fastens them by means of the suckers on some surface, 
be it of rock, or shell, or the side of the glass jar in which they 
are kept, and being thus anchored it drags itself forward. The 
tentacles are of a violet hue, though when stretched to their 

Fig. 135. 




Fig. 134. 







greatest length they lose their color, and become almost white 
and transparent ; but in their ordinary condition the color is 
quite decided, and the rows along which they occur make as 
many violet lines upon the surface of the body. 

Almost the sole function of the spines seems to be that of pro 
tecting the animal, and enabling it to resist the attacks of its ene 
mies, the force of the waves, or any sudden violent contact with 
the rocks. The spines, when magnified, are seen to be finely ribbed 
for nearly the whole length (Fig. 135), the bare basal knob serv 
ing as the point of attachment for the powerful muscles, which 
move these spines on a regular ball-and-socket joint, the ball sur 
mounting the tubercles (seen in Fig. 132), which fit exactly in a 
socket at the base of the spine. In a transverse section of a spine 
(Fig. 136), we see that the ribs visible on the outside are delicate 

Fig. 134. Sea-urchin seen from the mouth side. (Agassiz.) 
Fig. 135. Magnified spine. 



SEA-URCHIN. 105 

columns placed closely side by side, and connected by transverse 
rods forming an exceedingly delicate pattern. Beside the tentacles 
and the spines, they have other external appendages, of which 
the function long remained a mystery, and is yet but partially 
explained ; these are the so-called pedicellaria3 ; they consist of a 
stem (s, Fig. 137), which becomes swollen (j?, Fig. 137) into a 

Fig. 136. Fig. 137. 





thimble-shaped knob at the end (, Fig. 137) ; this knob may 
seem solid and compact at first sight, but it is split into three 
wedges, which can be opened and shut at will. When open, 
these pedicellariae may best be compared to a three-pronged fork, 
except that the prongs are arranged concentrically instead of on 
one plane, and, when closed, they fit into one another as neatly 
as the pieces of a puzzle. 

If we watch the Sea-urchin after he has been feeding, we 
shall learn, at least, one of the offices which this singular 
organ performs in the general economy of the animal. That 
part of his food which he ejects passes out at an opening on the 
summit of the body, in the small area where all the zones con 
verge. The rejected particle is received on one of these little 
forks, which closes upon it like a forceps, and it is passed on from 
one to the other, down the side of the body, till it is dropped off 
into the water. Nothing is more curious and entertaining than 
to watch the neatness and accuracy with which this process is 
performed. One may see the rejected bits of food passing rapidly 
along the lines upon which these pedicellaria? occur in greatest 
number, as if they were so many little roads for the conveying 

Fig. 136. Transverse section of spine ; magnified. 

Fig. 137. Pedicellaria of Sea-urchin ; * stem, p base of fork, t fork. 

14 



106 MARINE ANIMALS OF MASSACHUSETTS BAY. 

away of the refuse matters ; nor do tho forks cease from their 
labor till the surface of the animal is completely clean, and free 
from any foreign substance. Were it not for this apparatus the 
food thus rejected would be entangled among the tentacles and 
spines, and be stranded there till the motion of the water washed 
it away. These curious little organs may have some other office 
than this very laudable and useful one of scavenger, and this 
seems the more probable because they occur over the whole surface 
of the body, while they seem to pass the excrements only along 
certain given lines. They are especially numerous about the 
mouth, where they certainly cannot have this function ; we shall 
see also that they bear an important part in the structure of the 
Star-fish, where there are no such avenues on the upper surface, 
for the passage of the refuse food, as occur on the Sea-urchin. 

On opening a Sea-urchin, we find that the teeth (Fig. 138), 
which seem at first sight only like .five little conical wedges 
around the mouth (Fig. 134), are connected 
with a complicated intestine, which extends 
spirally from the lower to the upper floor of 
the body, festooning itself from one ambula 
cra! zone to the next, till it reaches the sum 
mit, where it opens. This intestine leads into 
the centre of the teeth, the jaws themselves, 
which siistain the teeth, being made up of a 
number of pieces, and moved by a complicated 
system of musciilar bands. When the intes 
tine is distended with food, it fills the greater part of the inner 
cavity ; the remaining space is occupied in the breeding season 
by the genital organs. In a section of the Sea-urchin, one may 
also trace the tube by which the supply of water, first filtered 
through the madreporic body, is conveyed to the ambulacra ; it 
extends from the summit of the body to the circular tube sur 
rounding the mouth. 

EchinaracTinius. (Echinarachnius parma GRAY.) 

Beside the Toxopneustes (Fig. 131) described above, we have 
another Sea-urchin very common along our shores. Among 

Fig 138. Teeth of Sea-urchin, so-called Lantern of Aristotle. 




ECHINARACHNIUS. 107 

children who live near sandy beaches, they are well known as 
" sand-cakes " (Fig. 139), and indeed they are so flat and 
round, that, when dried and deprived of their bristles, they look 
not unlike a cake with a star-shaped figure on its surface. (Fig. 
139.) When first taken from the water they are of a dark 
reddish brown color, and covered with small silky bristles. The 

Fig 139. 




disk is so flat, being but very slightly convex on the upper side, 
that one would certainly not associate it at first sight with the 
common spherical Sea-urchin or Sea-egg, as the Toxopneustes is 
sometimes called. But upon closer examination the delicate am- 
bulacral tubes or suckers may be seen projecting from along the 
line of the ambulacra, as in the spherical Sea-urchin ; and though 
these ambulacra become expanded near the summit into gill-like 
appendages, forming a sort of rosette in the centre of the disk, 
they are, nevertheless, the same organs, only somewhat more 
complicated. When such a disk is dried in the sun, and the 

Fig. 139. Echinarachnius, seen from above, with the spines on part of the shell ; a ainbulacral zone, 
i interambulacral zone. 



108 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 140. 



bristles entirely removed, the lines of suture of the plates com 
posing it, and corresponding exactly to those of the spherical 
Sea-urchin, may very readily be seen, (a and z, Fig. 139.) 

This flat Sea-urchin or Echinarachnius, as it is called, belongs 
to a group of Sea-urchins known as Clypeastroids (shield-like 
Sea-urchins). In a section (Fig. 140) exposing the internal 
structure, one cannot but be reminded by its general aspect of 

an Aurelia. Could one solidify 
an Aurelia it would present much 
the same appearance ; another evi 
dence that all the Radiates are 
built on one plan, their differences 
being only so many modes of ex 
pressing the same structural idea. 
The teeth or jaws in this flat Sea- 
urchin are not so complicated as in 
the Toxopneustes, being simply flat 
pieces, arranged around the mouth 
(o, Fig. 140), without the apparatus of muscular bands by means 
of which the teeth are moved in the other genus. It is a curious 
fact, considered in relation to the general radiate structure of 
these animals, that the teeth, instead of moving up and down like 
the jaws in Yerte"brates, or from right to left like those of Articu 
lates, move concentrically, all converging towards the centre. 




STAR-FISHES. 

Star-fish. (Astracanfliion berylinus AG.) 

Although there is the closest homology of parts between the 
Star-fish and the Sea-urchin, the arrangement of these parts, and 
the external appearance of the animals, as a whole, are entirely 
different. The Star-fish has zones corresponding exactly to those 



Fig. 140. Transverse section of Echinarachnius ; o mouth, e e ambulacra, c m atnbulacral ramifica 
tions, ww interambulacra. (Jlyassiz) 



STAR-FISH. 



109 



of the Sea-urchin, but instead of being drawn together, and united 
at the summit of the animal, so as to form a spherical outline, 
they are spread out on one level in the shape of a star. This 
change in the general arrangement brings the eye-specks to the 
extremities of the arms, and places the ovarian openings in the 
angles between the arms. The madreporic body is situated on 
the upper surface of the disk (Fig. 142), at the angle between 
two of the arms, and consequently between two of the ambulacra, 
and opposite the odd one. The tube into which it opens, runs 
vertically from the upper floor of the disk to the lower, where it 
connects with the circular tube around the mouth, and thus com 
municates with all the ambulacral rows. The ambulacral zones 
which, in the Star-fish, have the shape of a furrow, run along the 
lower side of each ray (Fig. 141) ; the interambulacral zones 
are divided, their plates being arranged in rows along either side 
of the ambulacral furrows. The ambulacral furrow, like the 
ambulacral zone in the Sea-urchin, is pierced with numerous 
holes, alternating with each other in a kind of zigzag arrange 
ment, one hole a little in advance, the next a little farther back, 
and so on, and through these holes pass the tenta 
cles, terminating in suckers, as in the Sea-urchins, 
and serving as in them for locomotive organs. The 
most prominent and strongest spines are arranged 
upon the large interambulacral plates on both sides 
of the ambulacral furrows ; but the upper surface of 
the animal is also completely studded with smaller 
spines, scattered at various distances, apparently 
without any regular arrangement. (Fig. 142.) 

The position of the pedicellarias is quite dif 
ferent from that which they occupy in the Sea- 
urchin, where they are scattered singly between 
the spines and tentacles, though more regularly 
and closely grouped along the lines upon which the refuse food 
is moved off. In the Star-fish, on the contrary, these singular 
organs seem to be grouped for some special purpose around the 
spines, on the upper surface of the body. Every such spine 
swells near its point of attachment, thus forming a spreading base 

Fig. 141. Star-fish ray, seen from mouth side. 




110 MARINE ANIMALS OF MASSACHUSETTS BAY. 

(Fig. 143), around which the pedicellariae are arranged in a close 
wreath, in the centre of which the summit of the spine projects ; 
they differ also from those of the Sea-urchin in having two 
prongs instead of throe. Other pedicellariae are scattered inde 
pendently over the surface of the animal, but they are smaller 

Fig. 142. 




than those forming the clusters and connected with the spines. 
The function of these organs in the Star-fish remains unexplained ; 
the opening on the upper surface, through which the refuse food 
is thrown out, is in such a position that they evidently do not 
serve here the same purpose which renders them so useful to the 
Sea-urchin. Occasionally they may be seen to catch small prey 

Fig. 142 Star-fish ; natural size, seen from above. 



STAR-FISH. Ill 

with these forks, little Crustacea, for instance ; but this is prob 
ably not their only office. The Star-fish has a fourth set of 
external appendages in the shape of little water-tubes. (Seen in 
Fig. 143.) The upper surface of the back consists of a strong 
limestone network (Fig. 144), and certain openings in this net 
work are covered with a thin membrane through which these 
water-tubes project. It is supposed that water may be intro 
duced into the body through these tubes ; but while there can be 

Fig. 144. 





no doubt that they are constantly filled with water, and are 
therefore directly connected with the circulation through the 
madreporic body (Fig. 145), no external opening has as yet been 
detected in them. The fact, however, that when these animals 
are taken out of their native element, the water pours out of them 
all over the surface of the back, so that they at once collapse and 
lose entirely their fulness of outline, seems to show that water 
does issue from those tubes. The ends of the arms are always 
slightly turned up, and at the summit of each is a red eye-speck. 
The tentacles about the eye become very 
delicate and are destitute of suckers. 

These animals have a singular mode of 
eating ; they place themselves over what 
ever they mean to feed upon, as a cockle 
shell for instance, the back gradually 
rising as they arch themselves above it ; 
they then turn the digestive sac or stom 
ach inside out, so as to enclose their prey 

Fig. 143. Single spine of Star-fish, with surrounding appendages ; magnified. 
Fir. 144. Limestone network of hack of Star-fish. 
Fig 145. Madreporic body of Star-fish ; magnified. 




112 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



completely, and proceed leisurely to suck out the animal from its 
shell. Cutting open any one of the arms we may see the yellow 
folds of the stomach pouches which extend into each ray ; within 
the arms, extending along either side of the upper surface, are 
also seen the ovaries, like clusters of small yellow berries. Im 
mediately below these, along the centre of the lower floor of each 
ray, runs the ridge formed by the ambulacral furrow, and upon 
either side of this ridge are placod the vesicles, by means of 
which the tentacles may be filled and emptied at the will of the 
animal ; the rest of the cavity of the ray is filled by the liver. 
The mouth, which is surrounded by a circular tube, is not fur 
nished with teeth, as in the Sea-urchin ; but the end of each 
ambulacral ridge is hard, thus serving the purpose of teeth. 



Fig 146. 



Cribrella. (Cribrella oculata FORBES.) 

Our coast, as we have said, is not rich in the variety of Star 
fishes. We have two large species, one of a dark-brown 
color (Fig. 132), the Astracanthion berylinus, and the other, 
the A. pallidus, of a pinkish tint ; then there is the small Cri 
brella, inferior in structural rank to the two above mentioned. 
(Fig. 146.) This pretty little Star-fish presents the greatest 

variety of colors ; some are 
dyed in Tyrian purple, others 
have a paler shade of the same 
hue, some are vermilion, others 
a bright orange or yellow. A 
glass dish filled with Cribrellas 
might vie with a tulip-bed in 
gayety and vividness of tints. 
The disk of the Cribrella is 
smooth, instead of being cov 
ered, like the larger Star-fishes, 
with a variety of prominent ap 
pendages. The spines are ex 
ceedingly short, crowded like 
little warts over the surface. It is an interesting fact, illustrat- 




Fig. 146. Cribrella from above 5 natural size. 



CTENODISCUS. 113 

ing again the correspondence between the adult forms of the 
lower orders and the phases of growth in the higher ones, 
that these spines have an embryonic character. One would 
naturally expect to find that these small spines of the adult Cri- 
brella would differ from those of the other full-grown Star-fishes 
chiefly in size, that they would bo a somewhat modified pattern 
of the same thing on a smaller scale ; but when examined under 
the microscope, they resemble the spines of the higher orders in 
their embryonic condition ; it is not, in fact, a difference in size 
merely, but a difference in degree of development. The Cri- 
brella moves usually with two of the arms turned backward, and 
the three others advanced together, the two posterior ones being 
sometimes brought so close to each other as to touch for their 
whole length. 

Hipp aster id. (Hippasteria phrygiana AG.) 

Beside these Star-fishes we have the pentagonal Hippasteria 
(Hippasteria phrygiana AG.), like a red star with rounded points, 
found chiefly in deep water, though it is occasionally thrown up 
on the beaches. It has but two rows of large tentacles, termi 
nating in a powerful sucking disk. The pedicellariae on this 
Star-fish resemble large two-pronged clasps, arranged principally 
along the lower side. The pentagonal Star-fishes of our coast 
are in striking contrast to the long-armed species we have just 
described ; they are edged with rows of large smooth plates, and 
do not possess the many prominent spines so characteristic of 
the ordinary Star-fishes. 

CtenodlSCUS. (Ctenodiscus crispatus T>. & K.) 

The Ctenodiscus {Ctenodiscus crispatus D. & K., Fig. 147), an 
inhabitant of more northern waters, but seeming also to be at 
home here occasionally, is another pentagonal Star-fish. It lives 
in deep water, and frequents muddy bottoms. The peculiar 
structure of their ambulacra has probably some reference to this 
mode of living, for they are entirely wanting in the sucking disks 
so characteristic of the other members of this class, and their 

15 




114 MARINE ANIMALS OF MASSACHUSETTS BAY. 

tentacles are pointed, 
as if to enable them 
to work their way 
through the mud in 
which they make their 
home. The pointed 
tentacles of this genus 
are characteristic of a 
large group of Star 
fishes, and it is an im 
portant fact, as show 
ing their lower stand 
ing, that this feature, 
as well as the pentag 
onal outline, obtains 
in the earlier stages 

of growth of our more common Star-fishes, while in their adult 
condition they assume the deeply indented star-shaped outline, 
and have suckers at the extremities of the tentacles. 

Solaster. (Solaster endeca FORBES.) 

We find also among Star-fishes the same tendency to multipli 
cation of parts so common among the Polyps and Acalephs. 
Our Solaster {Solaster endeca Forbes), for instance, has no less 
than twelve arms ; it inhabits more northern latitudes, though 
sometimes found in our Bay ; on the coast of Maine it is quite 
common, and occurs in company with another many-rayed spe 
cies, the Crossaster papposa M. & T. The color of both of these 
Star-fishes is exceedingly varied ; we find in the Solaster as many 
different hues as in the Cribrella, which it resembles in the struc 
ture of its spines, while in the Crossaster bands of different tints 
of red and purple are arranged concentrically, and the whole sur 
face of the back is spotted with brilliantly-tinged tiny wreaths of 
water-tubes, crowded round the base of the different spines, which 
are somewhat similar to those of the Astracanthion. 

Fig. 147. Ctenodiscus, seen from above : natural size. 




OPHIOPHOLIS. 



OPHIURANS. 



Ophiopholis. (Ophiopholis belli* LYM.) 



There are but two species of the ordinary forms of Ophiurans 
in Massachusetts Bay ; the white Amphiura {Amphiura squamata 
Sars), with long slender arms, and the spotted Ophiopholis (Fig. 
148), with shorter and stouter arms, and in which the disk is less 
compact than in the Amphiura, and not so perfectly circular. 

Fig. 148. 




All Ophiurans are difficult to find, from their exceeding shyness ; 
they hide themselves in the darkest crevices, and though no eye- 
specks have yet been detected in them, they must have some 
quick perception of coming danger, for at the gentlest approach 
they instantly draw away and shelter themselves in their snug 
retreats. 

Fig. 148. Ophiopholis, from above ; natural size. 



116 MARINE ANIMALS OF MASSACHUSETTS BAY. 

They differ from the Star-fishes in having the disk entirely 
distinct from the arms ; that is, the arms, instead of merging 
gradually into the disk, start at once from its margin. They 
have no interambulacral spaces or plates ; but the whole upper 
surface is formed of large hard plates, which extend from the 
back over the sides of the arms to their lower surface, where 
they form a straight ridge along the centre. (Fig. 149.) The sides 
of these plates are pierced with holes, through which the ten 
tacles pass ; these have not, like those of the Star-fishes and 
Sea-urchins, a sucker at the extremity, biit are covered with little 
warts or tubercles (Fig. 150) ; they are their locomotive ap- 



Fig. 150. 





pendages, arid their way of moving is curious ; they first extend 
one of the arms in the direction in which they mean to move, 
then, bring forward two others to meet them, three arms being 
thus usually in advance, and then they drag the rest of the body 
on. They move with much more rapidity, and seem more active, 
than the Star-fishes ; probably owing to the greater independence 
of the arms from the disk. The spines project along the mar 
gin of the arms, and not over the whole surface, the back of the 
arms being perfectly free from any appendages, and presenting 
only the surface of the plates. The madreporic body is formed 
by a plate on the lower side of the disk, in a position correspond- 

Fig 149. One arm of Fig. 148 ; from the mouth side. 
Fig. 150. Ambulacral tentacle of Ophiopholis ; magniaed. 



ASTROPHYTON. 117 

ing to that which it occupies in the young Star-fish ; this plate 
is one of the large circular shields occupying the interambulacral 
spaces around the mouth. (Fig. 149.) On each side of the arms, 
where they join the disk, are slits opening into the ovarian pouches. 
They have no teeth ; but the hard ridge at the oral end of the 
ambulacra, extending toward the mouth in Star-fish, is still more 
distinct and sharper in the Ophiurans, approaching more nearly 
the character of teeth. 

Astrophyton. (Astrophyton Agassizii STIMP.) 

A singular species of Ophiuran, known among fishermen as the 
" Basket-fish," (Fig. 151,) is to be found in Massachusetts Bay. 
Its arms are very long in comparison to the size of the disk, and 
divide into a vast number of branches. In moving, the animal 
lifts itself on the extreme end of these branches, standing as it 
were on tiptoe (Fig. 151), so that the ramifications of the arms 
form a kind of trellis-work all around it, reaching to the ground, 
while the disk forms a roof. In this living house with latticed 
walls small fishes and other animals are occasionally seen to take 
shelter ; but woe to the little shrimp or fish who seeks a refuge 
there, if he be of such a size as to offer his host a tempting mouth 
ful ; he will fare as did the fly who accepted the invitation of 
the spider. These animals are exceedingly voracious, and some 
times, in their greediness for food, entangle themselves in fishing- 
lines or nets. When disturbed, they coil their arms closely around 
the mouth, assuming at such times a kind of basket-shape, from 
which they derive their name. 

This Basket-fish is honorably connected with our early colonial 
history, being thought worthy, by no less a personage than John 
Winthrop, Governor of Connecticut, who, as he says, " had never 
seen the like," to be sent with " other natural curiosities of these 
parts " to the Royal Society of London, in 1670. He accom 
panies the specimen with a minute description, omitting " other 
particulars, that we may reflect a little upon this elaborate piece 
of nature." His account is as graphic as it is accurate, and we 
can hardly give a better idea of the animal than by extracting 
some portions of it. " This Fish," he says, " spreads itself from 



118 MARINE ANIMALS OF MASSACHUSETTS BAY 



Fig. 151. 




Fig. 151. Astrophyton, Basket-fish ; in a natural attitude. 



ASTROPHYTON. 119 

a Pentagonal Root, which incompasseth the Mouth (being in the 
middle), into 5 main Limbs or branches, each of which, just at 
issuing out from the Body, subdivides itself into two, and each of 
these 10 branches do again divide into two parts, making 20 lesser 
branches ; each of which again divide into two smaller branches, 
making in all 40. These again into 80, and these into 160 ; and 
these into 320 ; these into 640 ; into 1280 ; into 2560 ; into 5120 ; 
into 10,240 ; into 20,480 ; into 40,960 ; into 81,920 ; beyond 
which the further expanding of the Fish could not be certainly 
trac d"; a statement which we readily believe, wondering only 
at the patience which followed this labyrinth so far. 

In a later letter, after having had an interview with the fisher 
man who caught the specimen, and, as he says, " asked all the 
questions I could think needful concerning it," the Governor pro 
ceeds to tell us that it was caught " not far from the Shoals of 
Nantucket (which is an Island upon the Coast of New England)," 
and that when " first pull d out of the water it was like a basket, 
and had gathered itself round like a Wicker-basket, having taken 
fast hold upon that bait on the hook which he " (the fisherman) 
" had sunk down to the bottom to catch other Fish, and having 
held that within the surrounding brachia would not let it go, 
though drawn up into the Vessel ; until, by lying a while on the 
Deck, it felt the want of its natural Element ; and then voluntarily 
it extended itself into the flat round form, in which it appear d 
when present d to your view." The Governor goes on to reflect 
in a philosophical vein upon the purpose involved in all this com 
plicated machinery. " The only use," he says, " that could be 
discerned of all that curious composure wherewith nature had 
adorned it seems to be to make it as a purse-net to catch some 
other fish, or any other thing fit for its food, and as a basket of 
store to keep some of it for future supply, or as a receptacle to 
preserve and defend the young ones of the same kind from fish 
of prey ; if not to feed on them also (which appears probable 
the one or the other), for that sometimes there were found pieces 
of Mackerel within that concave. And he, the Fisherman, told 
me that once he caught one, which had within the hollow of its 
embracements a very small fish of the same kind, together with 
some piece or pieces of another fish, which was judged to be of a 



120 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Mackerel. And that small one ( t is like) was kept either for its 
preservation or for food to the greater ; but, being alive, it seems 
most likely it was there lodged for safety, except it were acci 
dentally drawn within the net, together with that piece of fish 
upon which it might be then feeding." The account concludes 
by saying, " This Fisherman could not tell me of any name it 
hath, and t is in all likelihood yet nameless, being not commonly 
known as other Fish are. But until a fitter English name be 
found for it, why may it not bo called (in regard of what hath 
been before mentioned of it) a Basket-Fish, or a Net-Fixh, or a 
Purs-net-Fish?" And so it remains to this day as the Governor 
of Connecticut first christened it, the Basket-fish. 



CRINOIDS. 

The Crinoids are very scantily represented in the present crea 
tion. They had their day in the earlier geological epochs, when 
for some time they remained the sole representatives of their class, 
and were then so numerous that the class of Echinoderms, with 
only one order, seemed as full and various as it now does with 
five. The different forms they assumed in the successive geo 
logical periods are particularly instructive ; these older Crinoids 
combined characters which foreshadowed the advent of the Oplii- 
urans, the true Star-fishes, and the Sea-urchins ; and so promi 
nently were their prophetic characters developed, that mUny of 
them are readily mistaken for Star-fishes or Sea-urchins. 

In later times the group of Crinoids has been gradually 
dwindling in number and variety. Its present representatives 
are the Pentacrinus of Porto Rico, attached throughout life to a 
stem, and the Comatula, which has a stem only in the early 
stages of its growth, but is free when adult. The Pentacrinus 
bears the closer relation to the more ancient Crinoids (Fig. 152), 
which were always supported on a stem, while it is only in more 



COMATULA. 



321 




recent periods that we find the free Crinoids, corresponding to 
the Comatula. 



Comatula. (Alecto meridionalis AG.) 

One large species of Comatula (Alecto Eschrichtii M. & T.) 
is known on our coast, off the shores of Greenland, wher6 it 
has been dredged at a depth of about one hundred and fifty 
fathoms, and young specimens of the same species have 
been found as far south as Eastport, Maine. The species 
selected for representation here, however, (Fig. 153,) is one 
quite abundant along the shores of South Carolina. It is intro 
duced instead of the northern one, because the latter is so rare 
that it is not likely to fall into the hands of our readers. The 
annexed drawing (Fig. 154, magnified from Fig. 153) repre 
sents a group of the young of the Charleston Comatula, still at 
tached to the parent body by their stems, and in various stages of 

Fig. 152. Foesil Pentacrinus. 



122 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



development. At first sight, the Comatula, or, as it is sometimes 

called, the feather- 
star, resembles an 
Ophiuran ; but on 
a closer examination 
we find that the arms 
are made up of short 
joints ; and along the 
sides of the arms, at 
tached to each joint, 
are appendages re 
sembling somewhat 
the beards of a feath 
er, and giving to each 
ray the appearance 
of a plume ; hence 
the name of feather- 
star. On one side 
the arms are covered 
with a tough skin, 
through which pro 
ject the ambulacra, 
and on the same side 
of the disk are situ 
ated the mouth and 
the anus ; the latter 
projects in a trum 
pet-shaped proboscis. 
On the opposite side 
of the disk the Co 
matula is covered 
with plates, arranged 
regularly around a 
central plate, which 
is itself covered with 
long cirri. 

Fig. 153. Comatula (Living Crinoid) seen from the back ; y group of young Comatulaa attached to 
parent. 
Fig. 154. Magnified view of the group of young Comatulae of Fig. 153. 




EMBRYOLOGY OF ECHINODERMS. 123 

We are indebted to Thompson for the explanation of the true 
relations of the young Comatula to the present Pentacrinus and 
the fossil Crinoids. Supposing these young to be full-grown 
animals, he at first described them as living representatives of 
the genus Pentacrinus ; it was only after he had watched their 
development, and ascertained by actual observation that they 
dropped from their stem, to lead an independent life as free 
Comatuke, that he fully understood their true connection with 
the past history of their kind, as well as with their contempora 
ries. In Fig. 153, a faint star-like dot (y) may be seen attached 
to the side of the disk by a slight line. In Fig. 154, we have 
that minute dot as it appears under the microscope, magnified 
many diameters ; when it is seen to be a cirrus of a Comatula, 
with three small, Pentacrinus-like animals growing upon it, in 
different stages of development. In the upper one, the branching 
arms and the disk, with its many plates, are already formed ; 
and though in the figure the rays are folded together, they are 
free, and can be opened at will. In the larger of the two lower 
buds, the plates of the disk are less perfect, and the arms are 
straight and simple, without any ramifications, though they are 
free and movable, whereas, in the smaller one, they are folded 
within the closed bud. 



EMBRYOLOGY OF ECHINODERMS. 

All Radiates have a special mode of development, as distinct 
for each class as is their adult condition, and in none are the 
stages of growth more characteristic than in the Echinoderms. 
In the Polyps, the division of the body into chambers, so marked 
a feature of their ultimate structure, takes place early ; in the 
Acalephs, the tubes which traverse the body are hollowed out of 
its mass in the first stages of the embryonic growth, and we shall 
see that in the Echinoderms also, the distinctive feature of their 
structure, viz. the enclosing of the organs by separate walls, 
early manifests itself. This peculiarity gives to the internal 



124 MARINE ANIMALS OF MASSACHUSETTS BAY. 

structure of these animals so individual a character, that some 
naturalists, overlooking the law of radiation, as prevalent in them 
as in any members of this division, have been inclined to separate 
them, as a primary division of the animal kingdom, from the 
Polyps and Acalephs, in both of which the body-wall furnishes 
the walls of the different internal cavities, either by folding in 
wardly in such a manner as to enclose them, as in the Polyps, 
or by the cavities themselves being hollowed out of the general 
mass, as in the Acalephs. 

Star-fish. (Astracanthion.) 

The egg of the Star-fish, when first formed, is a transparent, 
spherical body, enclosing the germinative vesicle and dot. (See 
Fig. 155.) As soon as these disappear, the segmentation of the 
yolk begins ; it divides first into two portions (see Fig. 156), 
then into four, then into eight, and so on ; but when there are 
no more than eight bodies of segmentation (see Fig. 157), they 

Fig. 155. Fig. 156. Fig. 157. 






already show a disposition to arrange themselves in a hollow 
sphere, enclosing a space within, and by the time the segmenta 
tion is completed, they form a continuous spherical shell. At this 
time the egg, or, as we will henceforth call it, the embryo, escapes 
and swims freely about. (See Fig. 158.) The wall next begins 
to thin out on one side, while on the opposite side, which by com 
parison becomes somewhat bulging, a depression is formed (ma, 
Fig. 159), gradually elongating into a loop hanging down within 
the little animal, and forming a digestive cavity. (J, Fig. 160.) 
At this stage it much resembles a young Actinia. The loop 
spreads somewhat at its upper extremity, and at its lower end is 

Fig. 155. Egg of Star-fish. 

Fig. 156. Egg of Star-fish in which the yolk has been divided into two segments. 

Fig. 157. Egg in which there are eight segments of the yolk. 



EMBRYOLOGY OF ECUINODERMS. 



125 



an opening, which at this period of the animal s life serves a 
double purpose, that of mouth and anus also, for at this opening 
it both takes in and rejects its food. We shall see that before 
long a true mouth is formed, after which this first aperture takes 
its place opposite the mouth, retaining only the function of the 
anus. Presently from the upper bulging extremity of the diges- 

Fig. 158. Fig. 159. Fig. 160. Fig. 161. 







tivc cavity, two lappets, or little pouches, project (ivw 1 , Fig. 101) ; 
they shortly become completely separated from it, and form two 
distinct hollow cavities (ivw 1 , Fig. 102). Here begins the true 
history of the young Star-fish, for these two cavities will develop 
into two water-tubes, on one of which the back of the Star-fish, 
that is, its upper surface, covered with spines, will be developed, 

Fig. 162. Fig. 163. Fig. 164. 






while on the other, the lower surface, with the suckers and tenta 
cles, will arise. At a very early stage one of these water-tubes 
(w , Fig. 163) connects with a smaller tube opening outwards, 
which is hereafter to be the madreporic body (6, Fig. 163). 
Almost until the end of its growth, these two surfaces, as we 

Fig. 158. Larva just hatched from egg ; a thickened pole. 

Fig. 159. Larva somewhat older than Fig. 158 ; ma depression at thickened pole. 

Fig. 160. Larva where the depression has become a digestive cavity d, opening at a. 

Fig. 161. Earlets, w w (water-tubes), developed at the extremity of the digestive cavity d ; m mouth. 

Fig. 162. More advanced larva ; a d c digestive system, vibratile chord, m mouth. 

Fig. 163. Profile view of larva; b madreporic opening, w earlet, ad digestive system, m mouth, 
V t> vibratile chord. 

Fig. 164. Larva showing mode of formation of mouth m, by bending of digestive cavity o 



126 MARINE ANIMALS OF MASSACHUSETTS BAY. 

shall see, remain separate, and form an open angle with one 
another ; it is only toward the end of the development that they 
unite, enclosing between them the internal organs, which have 
been built up in the mean while. 

At about the same time with the development of these two 
pouches, so important in the animal s future history, the digestive 
cavity becomes slightly curved, bending its upper end sideways 

till it meets the outer wall, and forms 
a junction with it (w, Fig. 164). At 
this point, when the juncture takes 
place, an aperture is presently formed, 
which is the true mouth. The diges 
tive sac, which has thus far served as 
the only internal cavity, now contracts 
at certain distances, and forms three 
distinct, though connected cavities, as 
in Fig. 163 ; viz. the oasophagus lead 
ing directly from the mouth (m) to the 
second cavity or stomach (<2), which 
opens in its turn into the third cavity, 

the alimentary canal. Meanwhile the water-tubes have been 
elongating till they now surround the digestive cavity, extending 
on the other side of it beyond the mouth, where they unite, thus 
forming a Y-shaped tube, narrowing at one extremity, and divid 
ing into two branches toward the other end. (Fig. 165.) 

On the surface where the mouth is formed, and very near it on 
cither side, two small arcs arise, as v in Fig. 162 ; these are cords 
consisting entirely of vibratile cilia. They are the locomotive 
organs of the young embryo, and they gradually extend until 
they respectively enclose nearly the whole of the upper and lower 
half of the body, forming two large shields or plastrons. (Figs. 
165, 166.) The corners of these shields project, slightly at first 
(Fig. 165), but elongating more and more until a number of 
arms are formed, stretching in various directions (Figs. 166, 167), 
and, by their constant upward and downward play, moving the 
embryo about in the water. 

Fig. 165. Larva in which arms are developing, lettering as before ; e e" e " e*e 5 e 5 arms, o oesoph 
agus. 




EMBRYOLOGY OF ECIIINODERMS. 



127 



At this stage of the growth of the embryo, we have what seems 
quite a complicated structure, and might be taken for a complete 
animal ; this is after all but the prelude to its true Star-fish exist 
ence. While these various appendages of the embryo have been 
forming, changes of another kind have taken place ; on one of the 

Fi?. Ifid. 




two water-tubes above mentioned (w )? a * tne en( ^ nearest the di 
gestive cavity, a number of lobes are formed (t, Fig. 166) ; this is 
the first appearance of the tentacles. In the same region of the 
opposite water-tube (w) a number of little limestone rods arise, 
which eventually unite to form a continuous network ; this is the 

Fig 166. Adult Larva, so-called Brachiolaria, lettering as before ; r back of young Star-fish, t ten- 
tacl js of young Star-fish, // brachiolar appendages. 



128 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 167. 



beginning of the back of the Star-fish (r, Fig. 166), from which the 
spines will presently project. When this process is complete, the 
whole embryo, with the exception of the part where the young 
Star-fish is placed, grows opaque ; it fades, as it were, begins to 
shrink and contract, and presently drops to the bottom, where 

it attaches itself by means of 
short .arms (// , Fig. 166), 
covered with warts, which act 
w , as suckers, and are placed just 
above the mouth. As soon as 
the Star-fish lias thus secured 
w , itself, it begins to resorb the 
whole external structure de 
scribed above ; the water-tubes, 
the plastrons, and the compli 
cated system of arms connected 
V witli them, disappear within the 
little Star-fish ; it swallows up, 
so to speak, the first stage of its 
own existence ; it devours its 
own larva, which now becomes 
part and parcel of the new ani 
mal. Next the two surfaces, 
the back and lower surface, on 
which the arms are now marked 
out, while the tentacles, suck 
ers, and spines have already 
assumed a certain prominence, 
approach each other. At this 
time, however, the arms are 
not in one plane ; both the back 
and the lower surface are 
curved in a kind of spiral ; they begin to flatten ; the arms spread 
out on one level, and now the two surfaces draw together, 
meeting at the circumference, and enclosing between them the 
internal organs, which, as we have seen, are already formed and 
surrounded by walls of their own, before the two walls of the bod) 

Fig. 167. Fig. 166 seen in profile, lettering as l>efore. 




EMBRYOLOGY OF ECHINODERMS. 



129 



close thus over them. Fig. 168 represents the upper surface of 
the Star-fish just before this junction takes place. The compli 
cated structure of the Brachiolaria, as the larva of the Star-fish 
has been called, hitherto so essential to the life of the animal, by 
which it has been supported, moved about in the water, and. pro 
vided with food during its immature condition, has made a final 
contribution to its further development by the process of resorp- 
tion described above, and has wholly disappeared within the Star 
fish. At this stage the rays are only just marked out, as five 
lobes around the margin ; Fig. 169 represents the lower surface 
at the same moment, with the open mouth (w), around which 

Fig. 168. Fig. 170. 





the tentacles (t) are just beginning to appear ; while Fig. 170 
shows us the animal at a more advanced stage, after the two sur 
faces have united. It has now somewhat the outline of a Maltese 
cross, the five arms being more distinctly marked out, while the 
tentacles have already attained a considerable length (Fig. 171), 
and the dorsal plates have become quite distinct. Fig. 172 rep 
resents the same animal, at the same age, in profile. This period, 
in which we have compared the form of the Star-fish to that of a 
Maltese cross, is one of long duration ; two or three years must 
elapse before the arms will elongate sufficiently to give it a star- 
shaped form, and before the pedicellariae make their appearance, 

Fig. 163. Star-fish which has just resorbed the larva, seen from the back ; b madreporic opening. 
Fig. 169. Fig. 168, seen from the mouth side ; m mouth, t tentacles. 

Fig. 170. Young Star-fish which has become symmetrical, seen from the back ; t odd tentacle. 
17 



130 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



and it is only then that it can be at once recognized as the young 
of our common Star-fish. Even then, after it has assumed its ulti 




mate outline, it lacks some features of the adult, having only two 
rows of tentacles, whereas the full-grown Star-fish has four. 

Sea-ur chins. 

This extraordinary process of development which we have ana 
lyzed thus at length in the history of the Star-fish, but which is 

Fig. 174. 



Fig. 173. 





equally true of all Echinoderms, has been hitherto described (so 
far as it was known) under the name of the plutean stages of 

Fig. 171. Lower side of ray of young Star-fish ; m mouth, b madreporic body, eye-speck. 

Fig. 172. Young Star-fish seen in profile ; t odd tentacle at extremity of arm. 

Figs. 173, 174, 175. Young larvse of Toxopneustes in different stages of development ; e - e IT arms, 
v-v" vibratile chord, w w earlets (water-tubes), a od c digestive system, r -r " solid rods of arms, 
m mouth, b madreporic opening. 



EMBRYOLOGY OF ECHINODERMS. 



131 



growth. In these early stages the young, or the so-called larvae 
of Echinoderms, have received the name of Pluteus on account 
of their ever-changing forms. Let us look for a moment at the 
plutean stages of the Sea-urchin, as they differ in some points 
from those of the Star-fish. In the Pluteus of our common 
Sea-urchins (see Fig. 176), the arms are supported by a frame 
work of solid limestone rods, which do not exist in that of 
the Star-fish, and which give to the larva of the Sea-urchin a re 
markable rigidity. They are formed very early, as may be seen 



Fig. 175. 




in Fig. 173, representing the little Sea-urchin before any arms 
are discernible, though the limestone rods are quite distinct. 
Figs, 173, 174, 175, may be compared with Figs. 160, 162, 165, 
of the young Star-fish, where it will be seen that the general out 
line is very similar, though, on account of the limestone rods, the 
Pluteus of the Sea-urchin seems somewhat more complicated. In 



132 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. 176 the young Sea-urchin has so far encroached upon the 
Pluteus that it forms the essential part of the body, the arms and 

Fig. 176. 




rods appearing as mere appendages. Fig. 177 shows the same 
animal when we looked down upon it in its natural attitude ; the 
Sea-urchin is carried downward, and the arms stretch in every di 
rection around it. In Fig. 178 the Pluteus is already in process 
of absorption ; in Fig. 179 it has wholly disappeared ; in Figs. 

Fig. 176. Adult larva of Toxopneustes, / brachilar appendages. 



EMBRYOLOGY OF ECHIXODERMS. 



133 



180 and 181 we have different stages of the little Sea-urchin, with 
its spines and suckers of a large size and in full activity. The 



Tig. 17 



Fig. 178. 





Fig. 179. 




appearance of the Sea-urchin, as soon as this larva or Pluteus is 
completely absorbed, is much more like that of the adult than is 
the Star-fish at the same stages, in which, as we have seen, there 
is a transition period of considerable duration. 

Fig. 177. Fig. 176 seen endways. 

Fig. 178. The Sea-urchin resorbing the arms of the larva. 

Fig. 179. Half a young Sea-urchin immediately after resorption of the larva ; s" s" spines, t t am- 
bulacral tentacles. 



134 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



Fig. ISO. 





Fig. 180. Young Sea-urchin older than Fig. 179 ; 1 1 tentacles, s" s " spines. 

Fig. 181. Still older Sea-urchin 5 1 1 tentacles, a anus, p pedicellaritu 5 shell one sixteenth of an inch 
in diameter. 



EMBRYOLOGY OF ECHINODERMS. 135 

Opliiurans. 

Fig. 183 represents an Ophiuran undergoing the same process 
of growth, at a period when the larva is most fully developed, and 
before it begins to fail. By the limestone rods which support the 
arms, the Pluteus of the Ophiuran, here represented, resembles 
that of the Sea-urchin more than that of the Star-fish, while by 
the character of the water-tubes and by its internal organization 
it is more closely allied to the latter. It differs from both, how 
ever, in the immense length of two of the arms ; these arms 
being the last signs of its plutean condition to disappear ; when 
the young Ophiuran has absorbed almost the whole Pluteus, it 
still goes wandering about with these two immense appendages, 
which finally share the fate of all the rest. Fig. 182 represents 



Fig. 182. 




an Ophiuran at the moment when the process of resorption is 
nearly completed, though the arms of the Pluteus, greatly di 
minished, are still to be seen protruding from the surface of the 
animal. 

This mode of development, though common to all Echino- 

Fig. 182. Ophiuran which has resorbed the whole larva except the two long arms, y y limestone 
rods of young Ophiuran, r middle of back ; lettering as ia Fig. 183. 



136 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Fig. 183. 




Fig. 183. Larva of Ophiuran , c - e iv arms, r r iv solid rods, v v vibratile chord, w w water system, 
b madreporic bady, ad digestive system. 



EMBRYOLOGY OF ECHINODERMS. 137 

derms, appears under very different conditions in some of them. 
There are certain Star-fishes, Ophiurans, and Holothurians, pass 
ing through their development under what is known as the 
sedentary process. The eggs are not laid, as in the cases de 
scribed above, but are carried in a sort of pouch over the mouth 
of the parent animal, where they remain till they attain a stage 
corresponding to that of Fig. 168 of the Star-fish, and having 
much the same cross-shaped outline, when they escape from the 
pouch (as the young Ophiopholis, Fig. 184), and swim about for 
the first time as free animals. Fig. 185 represents a cluster of 

Tig. 184. Fig. 185. 





young Star-fishes of the sedentary kind at about this period. But 
while this mode of growth seems at first sight so different, we shall 
find, if we look a little closer, that it is essentially the same, and 
that, though the circumstances under which the development takes 
place are changed, the process does not differ. The little Star 
fish or Ophiuran, in the pouch, becomes surrounded by the same 
plutean structure as those which are laid in the egg ; it is only 
more contracted to suit the narrower space in which they have to 
move ; and the water-tubes on which the upper and lower sur 
faces of the body arise, the shields, spreading out into arms at the 
corners, exist, fully developed or rudimentary, in the one as much 
as in the other, and when no longer necessary to its external ex 
istence they are resorbed in the same way in both cases. This 
singular process of development has no parallel in the animal 

Fig. 184. Young Ophiuran which has resorbed the whole larva ; r middle plate of back. 
Fig. 185. Cluster of eggs of Star-fishes placed over the mouth of the parent. 
18 



138 MARINE ANIMALS OF MASSACHUSETTS BAY. 

kingdom, although the growth of the young Echinoderm on 
the Brachiolaria may at first sight remind us of the budding of 
the little Medusa on the Hydroid stock, or even of the passage of 
the insect larva into the chrysalis. But in both these instances, 
the different phases of the development arc entirely distinct ; the 
Hydroid stock is permanent, continuing to live and grow and per 
form its share in the cycle of existence to which it belongs, after 
the Medusa has parted from it to lead a separate life, or if the 
latter remains attached to the parent stock after it has entered 
upon its own proper functions. The life of the caterpillar, 
chrysalis and butterfly, is also distinct and definitely marked ; the 
moment when the animal passes from one into the other cannot 
be mistaken, although the different phases are carried on suc 
cessively and not simultaneously, as in the case of the Acalephs. 
But in the Echinoderms, on the contrary, though the aspect of the 
Brachiolaria, or plutean stage, is so different from that of the adult 
form, that no one would suppose them to belong to the same ani 
mal, yet these two stages of growth pass so gradually into one 
another, that one cannot say when the life of the larva ceases, and 
that of the Echinoderm begins. 

The bearing of embryology upon classification is becoming 
every day more important, rendering the processes of develop 
ment among animals one of the most interesting and instruc 
tive studies to which the naturalist can devote himself, in the 
present state of his science. The accuracy of this test, not only 
as explaining the relations between animals now living, but as 
giving the clew to their connection with those of past times, can 
not but astonish any one who makes it the basis of his investiga 
tions. The comparison of embryo forms with fossil types is of 
course difficult, and must in many instances be incomplete, for 
while, in the one case, death and decay have often half destroyed 
the specimen, in the other, life has scarcely stamped itself in 
legible characters on the new being. Yet, whenever such com 
parisons have been successfully carried out, the result is always 
the same ; the present representatives of the fossil types recall in 
their embryonic condition the ancient forms, and often explain 
their true position in the animal kingdom. One of the most re 
markable examples of this in the type we are now considering, 



EMBRYOLOGY OF ECHINODERMS. 139 

is that of the Comatula already mentioned. Its condition in 
the earlier stages of growth, when it is provided with a stem, at 
once shows its relation to the old stemmed Crinoids, the earliest 
representatives of the class of Echinoderms. 

These coincidences are still more striking among living ani 
mals, where they can be more readily and fully traced, and often 
give us a key to their relative standing, which our knowledge of 
their anatomical structure fails to furnish. This is perhaps no 
where more distinctly seen than in the typo of Radiates, where 
the Acalephs in their first stages of growth, that is, in their Hy- 
droid condition, remind us of the adult forms among Polyps, 
showing the structural rank of the Acalephs to be the highest, 
since they pass beyond a stage which is permanent with the 
Polyps ; while the adult forms of the Acalephs have in their turn 
a certain resemblance to the embryonic phases of the class next 
above them, the Echinoderms. Within the limits of the classes, 
the same correspondence exists as between the different orders ; 
the embryonic forms of the higher Polyps recall the adult forms 
of the lower ones, and the same is true of the Acalephs as far 
as these phenomena have been followed and compared among 
them. In the class of Echinoderms the comparison has been 
carried out to a considerable extent, their classification has 
hitherto been based chiefly upon the ambulacral system, so 
characteristic of the class, but so unequally developed in the 
different orders. This places the Holothurians, in which the 
ambulacral system has its greatest development, at the head of 
the class ; next to them come the Sea-urchins or Echinoids ; 
then the Star-fishes ; then the Ophiurans and Crinoids, in which 
the ambulacral system is reduced to a minimum. Another 
basis for classification in this type, which gives the same re 
sult, is the indication of a bilateral symmetry in some of the 
orders. In the Holothurians, for instance, there is a decided 
tendency toward the establishment of a posterior and anterior 
extremity, of a right and left, an upper and lower side of the 
body. In the Sea-urchins, in many of which the mouth is out 
of centre, placed nearer one side than the other, this tendency 
is still apparent, while in the three lower groups, the Star-fishes, 
Ophiurans, and Crinoids, it is almost entirely lost, in the equal 



140 MARINE ANIMALS OF MASSACHUSETTS BAY. 

division of identical parts radiating from a common centre. A 
comparison of the embryonic and adult forms in these orders, 
confirms entirely this classification based npon structural features. 
The Star-fishes, in their earlier stages, resemble the mature Ophi- 
urans, while the Crinoids, the lowest group of all, retain through 
out their whole existence many features characteristic of the 
embryonic conditions of the higher Echiiioderms. In this prin 
ciple of classification, already so fertile in results, we may hope to 
find, in some instances, the solution of many perplexing points 
respecting the structural rank of animals, the confirmation of 
classifications already established ; in others, an insight into the 
true relations of groups which have hitherto been divided upon 
purely arbitrary grounds. 



DISTRIBUTION OF LIFE IN THE OCEAN. 141 



DISTKIBUTION OF LIFE IN THE 
OCEAN. 

WE have seen that while our bay is rich in certain species, it is 
wholly deficient or but scantily supplied with others, and that 
the character of the animals inhabiting its waters is more or less 
directly connected with general physical conditions. Such an 
area, limited though it be, gives us some insight into the laws 
which, in their wider application, control the distribution of ma 
rine life along the shores of the most extensive continents. The 
coast of Massachusetts, taken as a whole, is like that of New 
England generally, a rocky coast ; yet it has its sandy and muddy 
beaches, and though it lies for a great part open to the sea, it has 
nevertheless its sheltered harbors, its quiet bays and snug re 
cesses. 

A comparison of these limited localities with far more exten 
sive reaches of shore, where similar physical conditions prevail, 
shows that they reproduce, in fainter and less various characters 
of course, in proportion to their narrower boundaries, but still 
with a certain fidelity, the same combinations of animal and 
vegetable life. In other words, a sandy beach, however small, 
gives us some idea of the nature of the animals we may look for 
on any sandy coast, as, for instance, clams of various kinds, 
razor-shells, quahogs, snails, &c., creatures who can penetrate 
the sand, drag themselves through it or over it, leaving their 
winding trails as they go, and to whom the conditions prevailing 
in such spots are genial. So the narrowest mud flat on the sea 
shore or muddy beach will give us the same dead and inanimate 
aspect which characterizes a more extensive coast of like charac 
ter, where the gases always generated in mud are deadly to 
many kinds of animals, and the beings who find a home there 
are of closely allied species, chiefly a variety of worms, who bur 
row their way into the mud, and seem to court the miasma so 



142 MARINE ANIMALS OF MASSACHUSETTS BAY. 

fatal to other creatures. The same is true of any stony beach or 
rocky shore not more than a quarter of a mile in length ; it gives 
us an idea of the animal population on any similar coast of great 
er extent. 

These correspondences are of course modified by differences 
in climatic conditions. The animals on a sandy beach or a rocky 
shore, on the coast of Great Britain, for instance, are not absolute 
ly identical with those of a sandy beach or a rocky shore on the 
coast of New England, but they are more or less nearly related 
to them. Naturalists refer to this reiteration, all the world over, 
of like organic combinations under similar circumstances, when 
they speak of " representative species." The aggregate result is 
the same, though the individual forms are slightly modified. 
And here lies one secret of the infinite variety in nature, by 
which the old seems ever new, and the same thought has an eter 
nal freshness and originality, endlessly repeated, yet never hack 
neyed. 

In this sense our bay presents, on a miniature scale, a variety 
of physical and organic combinations, which may be compared to 
those more extensive divisions in the geographical distribution of 
animals and plants, called by naturalists zoological or botanical 
provinces or districts, the animal and vegetable populations of 
which are technically designated as their faunae and florae. Such 
organic realms, as we may call them, have long been recognized 
on land, and the most extensive among them are easily distin 
guished. No one will fail to recognize the tropical zone, with its 
royal dynasty of palms and all the accompanying glories of a trop 
ical vegetation, its birds of brilliant plumage, its large Mammalia, 
lions, tigers, panthers, elephants, and its great rivers haunted by 
gigantic reptiles. Nor is the representation of vegetable and ani 
mal life less characteristic in the temperate zone, where the oak 
is monarch of the woods, with all his attendant court of elms, 
walnuts, beeches, birches, maples, and the like, where birds of 
more sober hues, but sweeter voices, take the place of the bril 
liant parrots and many-tinted humming-birds of the tropical 
forest ; while buffaloes, bears, wolves, foxes, and deer represent 
the larger Mammalia. In the arctic zone, though marked by 
peculiar and distinctive features, vegetation has dwindled to a 



DISTRIBUTION OF LIFE IN THE OCEAN. 143 

minimum ; the birds are chiefly gulls and ducks, which go 
there for the breeding season in the summer, and the reindeer 
and polar bears are almost sole possessors of the snow and ice 
fields ; but this meagreness in the representation of the larger 
land Mammalia is amply compensated in the numbers of heavy 
aquatic Mammalia, the whales, walruses, seals, and porpoises of 
the Arctic seas. 

During the last half-century, since the geographical distribu 
tion of animals and plants has become a subject of more careful 
investigation among naturalists, these broad zones of the earth s 
surface, with their characteristic populations and vegetation, have 
been subdivided, according to more limited and special combina 
tions of organic forms, into narrower zoological and botanical 
areas. The application of these results to marine life is however 
of much more recent date, and indeed it would seem at first 
sight, as if the water, from its own nature, could hardly impose a 
barrier so impassable as the land. The localization of the marine 
faunaB and florae is nevertheless as distinct as that of terrestrial 
animals and plants, and late investigations have done much 
to explain the connection of this distribution with physical con 
ditions. 

A glance at the coast of our own continent, starting from the 
high north and making the circuit of its shores, from Baffin s 
Bay to Behring s Straits, will show us to what a variety of physi 
cal influences the animals who live along its shores are subjected. 
On the shores of Baffin s Bay, especially on the inner coast of 
Greenland, where the glaciers push their way down to the very 
brink of the water, and annually launch their southward-bound 
icebergs, we shall hardly expect to find a very abundant littoral 
fauna. On its western shore, where the ice does not advance so 
far, and a greater surface of rock is exposed, the circumstances 
are more favorable to the development of animal life. Here 
abound the winged Mollusks (Pteropods), often swept down to 
the coast of Nova Scotia by the cold current from Baffin s Bay ; 
the " whale feed," as the fishermen call them, because the whales 
devour them voraciously. Here occur also many compound 
Mollusks, especially a variety of Ascidians, and the highly colored 
stocks of Bryozoa. With them is found the Comatula of the 



144 MARINE ANIMALS OF MASSACHUSETTS BAY. 

northern waters, one of the few modern Crinoids, and beside 
these a number of Star-fishes, Sea-urchins, and Holothurians, not 
differing so essentially from those already described as to require 
special mention. 

Along the shore of Labrador and Newfoundland, the coast is 
wholly rocky, and especially about Newfoundland it is deeply in 
dented with bays. Here there is ample opportunity for the 
growth of certain kinds of animals in sheltered nooks. The 
number of species is, however, much greater along the shores of 
Maine, Nova Scotia, and New Brunswick than in Labrador, 
owing no doubt to the milder climate. The beautiful shore of 
Maine, with its countless islands, and broken, picturesque outline, 
is very rich in species. Parts of this coast are remarkable for a 
variety of naked Mollusks, as well as the great numbers of 
bright-colored Actiniae, and also for the more brilliant kinds of 
Holothurians, the Cuvieria, and the like. The latter are especially 
abundant in the Bay of Fundy, and here also occurs the only 
Northern representative on our coast of the Sea-fans or Gorgonias, 
so common on the shores of Florida. 

Farther south, from Cape Cod to Cape Hatteras, the character 
of the coast changes ; it becomes more sandy, and though here 
and there the aspect is varied by a rocky promontory or a stony 
beach, yet the general character is flat and sandy. With this 
new character of the shore, the fauna is also greatly modified, and 
it is worthy of remark, that while thus far the representative 
species have reflected the character of animals to the north of 
them, they now begin to represent rather those of the Carolina 
shores. South of Cape Cod come in a kind of Scallop and Peri 
winkle, very different from the larger Scallops found on the coast 
of Maine and the British Provinces ; our Sea-urchin is replaced 
by the Echinocidaris, with its few long spines, and an entirely new 
set of Crustacea and Worms make their appearance on this more 
sandy bottom. And here we must not forget that not only is the 
aspect of the animal life changed, as we pass from a rock-bound 
to a sandy coast, but that of the vegetation also. The various 
many-tinted sea-weeds of the rocky shore disappear almost en 
tirely, and their place is but poorly supplied by the long eel- 
grass, which is almost the only marine plant to be found in such 



DISTRIBUTION OF LIFE IN THE OCEAN. 145 

a locality. Beside its more sandy character, the coast from Capo 
Cod to Cape Hatteras is affected by the large amount of fresh 
water poured into the sea along its whole line, greatly modifying 
the character of the shore animals. The Hudson, the Delaware, 
the Susquehanna, the Potomac, the James, the Roanoke, and the 
large estuaries connected with some of these rivers, give a very 
peculiar character to the shore, and bring down, not only a vast 
supply of fresh water, but also a large quantity of detritus of all 
sorts from the land. Under these circumstances life would be 
impossible for many of the animals which live farther north. 
The only locality on the North Atlantic shore, where the condi 
tions are somewhat similar, is at the mouth of the St. Lawrence, 
that great drainage-bed through which the Canadian lakes empty 
their superfluous waters into the Gulf of St. Lawrence. 

The whole coast of the Carolinas, from Cape Hatteras to 
Florida, is a sandy beach ; but though in this respect it resembles 
that immediately to the north of it, it differs greatly in other 
features. Comparatively little fresh water is poured into the 
ocean along this shore, and its more southerly range, instead 
of being protected by sand-spits like Pamlico and Albemarle 
Sounds, or broken by estuaries and inlets like the coast of Vir 
ginia, lies broadly open to the sea. On its extensive beaches 
we have the large Pholas, burrowing deep below the surface, 
and the Cerianthus, those long, cylindrical Actiniae, enclosed in 
sheaths, with their bright crowns of gayly-colored tentacles ; the 
free colonies of Halcyonoids abound also on this coast, and a new 
set of Sea-urchins (Spatangoids and Clypeastroids) make their 
appearance. 

Farther south, along the Florida coast, a new element comes 
in, that of the coral reefs, enclosing shallow channels near the 
shore, and thus providing sheltered harbors on their leeward side, 
while on their seaward side they slope steeply to the ocean. Be 
side this, the reef itself affords a home for a great variety of 
creatures, who bore their way into it and live in its recesses, as 
some insects live in the bark of trees. Perhaps a more favor 
able combination of circumstances for the development of marine 
life does not exist anywhere than about the coral reefs of 
Florida, and certainly nowhere is there a more rich and varied 

19 



146 MARINE ANIMALS OF MASSACHUSETTS BAY. 

littoral fauna, especially on their western shore within the Gulf 
of Mexico. Here swims the Portuguese Man-of-War, borne gayly 
along on the surface of the water by its brilliant float, here the 
blue Velella sets its oblique sail to the wind, and hosts of the 
lighter and more brightly tinted corals fringe the shore with a 
many-colored shrubbery. In these waters are also found the blue 
and yellow Angel-fish, the Parrot-fish (Scams), and the strange 
Porcupine-fish (Diodon). Vegetable life is comparatively scanty 
in these tropical waters, where there are scarcely any sea-weeds, 
except the corallines or limestone Alga3 of the reefs. The shore 
of the Gulf of Mexico, as a whole, has much the same character 
as that of the Carolinas, until we reach the point where the 
mountains and plateau of Mexico come down to the coast. From 
this point to the Isthmus of Panama the coast is again rocky. 

Crossing the Isthmus and following the Pacific shore of the 
continent northward, we find a sandy open shore alternating with 
rocky beaches as far north as Acapulco. Along this coast there 
is to be found a great variety of corals, especially Sea-fans, 
growing on the rocks, but no reef. The Pocillopora, an Acale- 
phian coral, the Pacific representative of the Millepore of Florida, 
is especially abundant. On the peninsula of Lower California we 
come again upon a rocky coast, with steep bluffs, extending into 
the sea. Within the Gulf of California are found, on its sandy 
coast, peculiar kinds of Sea-urchins, Spatangoids, and Clypeas- 
troids, which occur nowhere else on this coast. From Cape St. 
Lucas up to the Straits of Fuca, with the exception of the large 
fresh-water estuary which forms the port of San Francisco, there 
is not a harbor of any consequence. The whole shore is most 
inhospitable, and the violent northwest winds in summer, and 
the southeast winds in winter, render it still more bleak and diffi 
cult of approach. In consequence of these conditions, the fauna 
is scanty along a great part of the shore ; the best spots for collect 
ing are the beaches, near the head of the peninsula, opposite the 
islands of Santa Barbara and San Diego, and that within the 
harbor of San Francisco. On the former, large Craw-fishes abound 
(Palinurus), akin to those of Florida, though specifically different 
from them. In the latter, the great amount of fresh water 
prevents the fauna from being exclusively marine ; this harbor is, 



DISTRIBUTION OF LIFE IN THE OCEAN. 147 

nevertheless, the great centre of the viviparous fishes, and con 
tains also a large variety of peculiarly shaped Sculpins. 

Farther north, between the Straits of Fuca and the island of 
Sitka, the shore resembles that of Maine, with its many islands, 
bays, and inlets ; a succession of long, narrow islands forms a 
barrier along the coast, enclosing the shore waters, so as almost 
to make them into an inland sea. But little fresh water empties 
upon this part of the coast, and here, where the salt water is little 
modified by any deposit from the land, but where the violence of 
the ocean is broken by this barrier of islands, there is a full devel 
opment of marine life. The shores of the Gulf of Georgia, and 
those of Vancouver s Island, seem to be especially the home of 
the Star-fishes. The fauna of this locality has been but little in 
vestigated, and yet the number of species of Star-fishes known 
from there is greater than from any other region ; many of them 
are of colossal size, measuring some four feet in diameter. This 
coast seems also very favorable for the development of Hydroids, 
in consequence of which its waters swarm with a variety of Jelly- 
fishes. The Pennatula, that pretty compound Halcyonoid, with 
its feather-like sprays, is another characteristic type of this fauna. 
Beyond this, from Sitka to Behring s Straits, the same rocky 
coast prevails as in Labrador and Greenland. In Behring s 
Straits we return again to the forests of beautiful compound 
Mollusks, or rather to a variety of "representative species," 
resembling the Bryozoa and Ascidians so abundant in Baffin s 
Bay. The depth of the water, however, is much less here than 
on the corresponding Atlantic coast, where, south of Greenland, 
along the shore of Labrador, the water is very deep, while in 
Behring s Straits the depth is not greater than from one hundred 
to one hundred and twenty fathoms. The respective faunae of 
these two shores is also affected by the difference of temperature, 
the cold current from Baffin s Bay sweeping down upon the coast 
of Labrador, while, through Behring s Straits, the warm current 
from the Pacific pours into the Arctic Ocean. 

Thus the whole coast of our continent is peopled more or less 
thickly with animals. But now arises a new set of inquiries ; 
how far into the sea do these animals extend ? how wide is their 
domain ? Do they wander at will in the ocean, or are they 



148 MARINE ANIMALS OF MASSACHUSETTS BAY. 

bound by any law to keep within a certain distance of the shore ? 
These questions would seem to be easily answered, for wherever 
we go on the surface of the sea, and as far as the eye can pene 
trate into its depths, we find it full of life ; and yet a closer ex 
amination shows that all these beings have their appointed boun 
daries. Along the shores, animal and vegetable life seems to be 
distributed in certain definite combinations. Those who are 
familiar with rocky beaches readily recognize the different bands 
of color produced by the various kinds of sea-weed growing at 
given distances between high and low-water-mark. First comes 
the olive green rockweed (the Fucus), and with it are found bar 
nacles and small Crustacea, myriads of which are to be seen hop 
ping about in this rockweed when the tide is out. Below these 
are the brown crispy Rhodersperms and Melanosperms, and asso 
ciated with them are Star-fishes, Crabs, and Cockles. Next in 
order is the Laminarian zone. Here we have the broad fronds 
of the Laminaria, the " devil s aprons," as the fishermen call 
them ; in this zone is the home of the Sea-urchin, and here will 
be found also a few small fishes. Lastly we have the Coralline 
zone, so called on account of the lime deposit in the sea-weeds, 
giving them the rigidity of corals ; among these the Lobsters 
make their appearance, and here are to be found also numerous 
clusters of Hydroids, the nurses of the Jelly-fishes. 

This distribution is not casual ; these belts of animal and vege 
table life are sharply defined and so constantly associated, that 
they must be controlled by the same physical laws. The first 
important investigations on this subject were made by Orsted, 
the distinguished Danish naturalist. He undertook a complete 
topographical survey of the coast near which he lived, carrying 
his soundings to a depth of some twelve fathoms, and found that 
both the fauna and flora of the shore were divided, according to 
the depth of the water, into bands of vegetable and animal life, 
corresponding very nearly with those given above. His observa 
tions were, however, limited, not extending beyond the neighbor 
hood of his home. It is to Edward Forbes, the great English 
naturalist, whose short life was so rich in results for science, that 
we owe a more complete and extensive investigation of the whole 
subject. 



DISTRIBUTION OF LIFE IN THE OCEAN. 



149 




Diagram of a rocky beach. 



150 MARINE ANIMALS OF MASSACHUSETTS BAY. 

Aided by a friend, Captain McAndrew, who placed his yacht 
at his disposal, he made a series of observations on the British, 
Scandinavian, and Danish coasts, and explored also with the 
same object the shores of the Mediterranean. Not content with 
sounding the present ocean, he sunk his daring plummet in the 
seas of past geological ages, and by comparing the nature and 
position of their fossil remains with those of living marine faunae, 
he measured the depths of the water along their shores. He col 
lected a vast amount of material, and the results of his labors 
have formed the basis of all subsequent generalizations upon this 
subject. Nevertheless he arrived at some erroneous conclusions, 
which, had he lived, he would no doubt have been the first to 
correct. Dredging from low-water-mark outward, he found that, 
from the Laminarian and Coralline zone, the animals began grad 
ually to decrease in number, and that, at a depth of two or three 
hundred fathoms, the dredge always came up nearly empty. 
He inferred that at a certain depth the weight of water became 
too great to be endured by animals, and that the ocean beyond 
this line, like the land beyond the line of perpetual snow, was 
barren of life. This result seemed the more probable on account 
of the immense pressure to which animals are subjected, even at 
a comparatively moderate depth. A column of water thirty-two 
feet high is equal to one atmosphere in weight ; this pressure 
being increased to the same amount for every thirty-two feet of 
depth, it follows that a fish one hundred and twenty-eight feet, or 
some twenty fathoms below the surface, is under the pressure of 
almost four atmospheres plus that of the air outside. Wherever 
tides run high, as in the Bay of Fundy, for instance, where an 
animal is under the pressure of one atmosphere at low tide, and 
of three atmospheres at high tide, we see that marine animals are 
uninjured by great changes of pressure. Yet it seems natural to 
suppose that there is a limit to this power of resistance ; and 
that there must exist barren areas at the bottom of the ocean, as 
destitute of life as the regions on the earth which are above the 
line of perpetual snow. No doubt pressure does influence the 
distribution of life in the ocean ; but it would seem, from subse 
quent observations, that the boundaries assigned by Forbes were 
far too narrow, and that the structure of many marine animals 



DISTRIBUTION OF LIFE IN THE OCEAN. 151 

enables them to live under a weight, the one hundredth part of 
which would be fatal to any terrestrial animal. 

For some years Forbes s theory was very generally accepted, 
and the results of Darwin s and Dana s investigations, showing that 
corals could not live beyond a depth of fifteen fathoms, eemed to 
confirm it. But, quite recently, facts derived from new and 
unlocked for sources of information have given a check to this 
theory. Practical objects, the interests of commerce have come 
to the aid of science (rewarding her for the gift first received at 
her hands), and the telegraph cables, alive with the secrets of sea 
and land, have brought us tidings from the deep. In the Medi 
terranean and in the Red Sea, from depths of eighteen hundred 
to two thousand fathoms, living animals have been brought up on 
the telegraph wires, not of doubtful infusorial character, hovering 
on the border-land between animal and vegetable life, but of con 
siderable size, as for instance, one or two kinds of Crustacea, 
Cockles, stocks of Bryozoa and tubes of Annelids. When the 
cable between France and Algiers was taken up from a depth of 
eighteen hundred fathoms, there came with it an Oyster, Cockle 
shells, Annelid tubes, Bryozoa and Sea-fans. As these animals 
were growing upon it, there could be no doubt that they had 
their normal life and development at this depth, and since they 
are carnivorous, they tell also of the existence of other animals 
with them on which they feed. This discovery alone shows how 
much yet remains to be done before we shall fully understand 
the laws of marine life. But we already have ample evidence 
that the same beneficent order controls the distribution of ani 
mals in the ocean as on land, appointing to all its inhabitants 
their fitting home in the dim waste of waters. 



SYSTEMATIC TABLE 



OF THE ANIMALS DESCRIBED IN THIS VOLUME. 



RADIATA. 



CLASS I. -POLYPI. 



ORDER I. ACTINARIA EDW. 

Metridium marginatum EDW. 
Rhodactinia Davisii AG. 
Bicidium parasiticum AG. 
Arachnactis brachiolata A. AG. 
Halcampa albida AG. 



ORDER H. M ADREPORI A AG. 

Astrangia Dance AG. 

ORDER HI. HALC F ONARIA EDW. 

Halcyonium carneum AG. 



CLASS II. ACALEPHJE. 



ORDER I. HYDROIDEA JOHNST. 

Velella mutica Bosc. 
Physalia Arethusa TIL. 
Nanomia cam A. AG. 
Millepora alcicornis LIN. 
Hydractinia polydina AG. 
Tubularia Couthouyi AG. 
Hybocodon prolifer AG. 
Coryne mirabUis AG. 
Turris vesicaria A. AG. 
Bougainvillia superciliaris AG. 
Dysmorphosa fulgurans A. AG. 
Dynamena pumila LAMX. 
Dyphasia rosacea AG. 
Lafcea cornuta LAMX. 
Melicertum carnja^ffula PER. et LES. 
Ptychogena laciea A. AG. 
Laomedea amphora AG. 



Zygodactyla groenlandica AG. 
Tima formosa AG. 
Eucope diaphana AG. 
Clytia bicophora AG. 
Oceania languida A. AG. 

ORDER H. DISCOPHOR^E ESCH. 

Halyclistus auricula, CLARKE. 
Trachynema digitate A. AG. 
Campanella pachyderma A. AG. 
Cyanea arctica PER. et. LES. 
Aurelia flavidula PER. et LES. 

ORDER HI. CTENOPHOR^E ESCH. 

Idyia roseola AG. 
Pleurobrachia rhododactyla AG. 
Bolina alata AG. 



SYSTEMATIC TABLE. 



153 



CLASS III. ECHINODEBMATA. 



ORDER I. CRINOIDEA. 

Pentacrinus. 

Alecto EschricMi M. & T. 

Alec to meridionalis AG. 

ORDER H. OPHIURIDEA. 

Amphiura squamata SARS. 
Ophiopholis bellis LYM. 
Astrophyton Agassizii STIMP. 

ORDER III. ASTERIDEA. 

Ctenodixcus cr ispatus D. & K. 
Hippasteria pliryglana AG. 
Cribrella oculata FORBES. 



Solaster endeca FORBES. 
Crossaster papposa M. & T. 
Astracanthion pallid us AG. 
Astracantldon berylinus AG. 

ORDER IV. ECHINIDE.A. 

Toxopneustes drobacJiiensis AG. 
Echinarachnius parma GRAY. 

ORDER V. HOLOTHURIDEA. 

Caudina arenata STIMP. 
Synapta tennis AYRES. 
Cuvieria squamata D. & K. 
Pentacta frondosa, JAG. 



20 



INDEX. 



PAGE 

Acalephs, 21 

Actinia, 7 

Actinoids, 7 

Alecto Eschriclitii, 121 

Alecto meridionalis, 121 

Amphiura squamata, 115 

Arachnactis brachiolata, 14 

Astracanthion berylinus, 108 

Astracanthion pallidus, 112 

Astrangia Danse, 16 

Astrophyton Agassizii, 117 

Aurelia flavidula, 42 

Bicidium parasitieum, 15 

Bolina alata, 31 

Bougainvillia superciliaris, 69 

Campanella pachyderma, 44 

Campanularians, 49 

Caudina arenata, 97 

Circe, 45 

Clytia bicophora, 56 

Comatula, 121 

Coryne mirabilis, 68 

Cribrella oculata, 1 1 2 

Crinoids, 120 

Crossaster papposa, 114 

Ctenodiscus crispatus, 113 

Ctenophoras, 26 

Cuvieria squamata, 98 

Cyanea arctica, 38 
Development of Melicertum, 64 

" " Tima, 64 

Discophorae, 3 7 
Distribution of Life in the 

Ocean, 141 

Dynamena pumila, 66 



PAGE 

Dyphasia rosacea, 67 

Dysmorphosa fulgurans, 75 

Echinarachnius parma, 106 

Echinoderms, 91 

Echinoids, 101 

Embryology of Astracanthion, 124 

" " Ctenophorae, 34 

" " Echinoderms, 123 

" " Ophiurans, 135 

" " Sea-urchins, 130 

" " Star-fishes, 124 

Eucope diaphana, 30 

Halcampa albida, 16 

Haley onium carneum, 19 

Halcyonoids, 1 9 

Halyclistus aurirula, 46 

Hippasteria phrygiana, 113 

Holothurians, 95 

Hybocodon prolifer, 74 

Hydractinia polyclina, 73 

Hydroids, 49 

Idyia roseola, 32 

Lafoea cornuta, 67 

Laomedea amphora, 65 

Lucernaria, 46 

Madreporians, 1 6 

Melicertum campanula, 63 

Metridium marginatum, 7 

Millepora alcicornis, 22 

Mode of catching Jelly-fishes, 85 

Nanomia cara, 76 

Oceania languida, 53 

Ophiurans, 115 

Ophiopholis bellis, 1 1 5 

Pentacrinus, 121 



Pentacta frondosa, 

Pleurobrachia rhododactyla, 

Polyps, 

Ptychogena lactea, 

Physalia Arethusa, 

Radiates, 

Rhodactinia Davisii, 

Sarsia, 

Sea-urchin, 

Sertularians, 

Solaster endeca, 



INDEX. 155 

99 Star-fishes, 108 

27 Synapta tenuis, 95 

5 Systematic Table, 152 

86 Tima formosa, 60 

83 Toxopneustes drobachiensis, 101 

1 Trachynema digitale, 45 

13 Tubularia Couthouyi, 72 

68 Tubularians, 67 

101 Turris vesicaria, 69 

66 Velella mutica, 84 

114 Zygodactyla groenlandica, 57 



THE END. 



Cambridge : Stereotyped and Printed by Welch, Bigelow, & Co. 



Agassiz. 

Sea side studies* 



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BIOLOSY 
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