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SEASIDE STUDIES

NATURAL HISTORY.

BY

ELIZABETH C. AGASSIZ

\\

AND

ALEXANDER AGASSIZ.

MARINE ANIMALS OF MASSACHUSETTS BAY,
RADIATES.

BOSTON:
TICKNOR AND FIELDS.

1865.

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

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

UNIVERSITY PRESS:

WELCH, BIGELOW, AND COMPANY,

C AMBRI DGE.

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 Eadiates, 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, 1865.

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 RADIATES 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

2 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 inpre
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, Pe*roii
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 mvidness and freshness which nothing but
familiarity with' the living specimens can give. Besides these,
we have the admirable works of Von Siebold, of Ehrenberg,
the great interpreter o'f 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 die 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 hericeforth 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, Jager. Des-
moulins, Troschel, Sars, Savigny, Forbes, Agassiz, and Liitken,
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 varioiis
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 featnres 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 be our own fault if our readers are not attracted by the many graceful forms to
which we shall then introduce them.

GENERAL SKETCH OF THE POLYPS.

GENERAL SKETCH OF THE POLYPS.

Fig- 1.

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. (Jgassiz.)

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" and:* 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 Habyonpiid^; '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 throughout 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. / ,

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 consequently. 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 Pennatula3,
well known on the California coast, or working their way through
the sand like the Eenilla, 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, and 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. (Agassiz.}

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 occiir 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 fiat
2

10 MARINE ANIMALS OF MASSACHUSETTS BAY.

and slightly spreading around the margin. (Fig. 2.) The upper
edge of this bag turns in so as to form a sac within a sac. (Fig.
rig. 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 ^o 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 (0) and a secondary partition g' ; o mouth,
t tentacles, s stomach, ff reproductive organs, b main cavity, c openings in partitions, a lower floor, or
foot.

METRIDIUM.

11

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 Fig. 7.

of the body itself thins out to a ,,^,,,0^

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
contrary, be dropped from the par-
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

Fig. 8.

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.

siimmit 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 on 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 on 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 Actiniae 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 north, 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
of fresh 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 Actinias 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. llhodactinia 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.

ArachnCLctis. ^Arachnactis brachiolata A. AG.)

Fig. 11.

Fig. 12.

Fig. 11.
Fig. 13.

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

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. 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 parasiticum Ao.)

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. u.
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.

. (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.

Astrangia. (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 rig. 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 surface. This film is,
however, broken up by a number of hard calcareous deposits in
very regular fbrm (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 rig. 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. Astranpia colony; 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,
Fig 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 Actiniae, 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.

HALCYONOIDS.

19

Fig. 20.

one fifth the height of the animal at its greatest extension. This
lime deposit does not, however, fill
the chamber for its whole width, but
rises as a thin wall in its centre. (See
Figs. 16, 17.) 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.

^tVJEX^

HALCYONOIDS.

(Halcyonium carneum AG.)

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- rig. 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 5 magnified.
Fig. 21. Single individual of Halcyonium seen from above; magnified.

20 MARINE ANIMALS OF MASSACHUSETTS BAY.

and fringed around the margin. Our Haley onium communities
F. 22 (Fig. 22) usually 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 plamilse 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 CTENOPHOR^E, so called on
account of their locomotive organs, consisting of minute flappers
arranged in vertical comb-like rows ; next to these are the Dis
COPHOB^B, 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
Ctenophorse grow from eggs by a direct continuous process of
development, without undergoing any striking metamorphosis ;
the Discophoras, 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- Fig. 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, Astraeans, 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

Fi}?. 26. Transverse section of a branch, showing pits, a a a a, of the large Ilydroids with the hori-
zontal floors. (J3ijassiz.~)

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 understood, 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.

CTENOPHOE^E.

THE Ctenophorae 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 throughout all its parts by means of
ramifying tubes. In the Ctenophora3 there is no such regular
expansion and contraction of the disk ; they are at once dis-
tinguished from the Diseophora3 by the presence of external
locomotive appendages of a very peculiar character. They move
by the rapid flapping 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 Ctenophorse 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 rhododactyla 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). Fi 27

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 JC

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
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. 28. Pleurobrachia seen in plane of tentacles. (Agassiz.)

PLEUROBRACHIA. 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 Fie 29>

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, chymiferoiis 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

Fig. 31.

Bolina. (Bolina alata AG.)

THE Bolina (Fig 32), like the Pleurobrachia, is slightly oval in
form, with a longitudinal split at one end of the body, forming a
mouth 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
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 on each side (Fig. 32), called auricles. These so-called
auricles 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, a f long rows of flappers, n x t z tubes winding in the larger lobes ; about half
natural size. (Agassiz.)

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

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.

Idyid. (Idyia. roseola AG.)

The lowest genus of Ctenophora3 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
rig 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. (Agassiz.)

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 CTENOPHOR^E.

ALL the Ctenophoraa 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 Ctenophoras. 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 Ctenophoroe.
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' rows of locomotive flappers; magnified.

Fig. 37. Young Idyia, greatly magnified 5 lettering as in Fig. 36 ; d digestive cavity.

36

MARINE ANIMALS OF MASSACHUSETTS BAY.

with its rapid gyrations, its short ambulacral 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 ; a anal opening, other letters as In
Fig. 36.

Fig. 39. Idyia somewhat older than Fig. 37, lettering as before 5 magnified.

Fig. 40. Young Idyia in which the ambulacral tubes begin to ramify 5 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 Ctenophorae 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^.

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 -ffo 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, o), 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 P£R. 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 DiscophoraB in the autumn, which has indeed been par-
rig. 45. Fig. 47. 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. Scyphistoraa of a Discophore ; Aurelia flavidula. (Agassiz.)
Fig. 46. Scyphistoma, older than Fig. 45. (Agassis.)
Fig. 47. Strobila of a Discophore ; Aurelia flavidula. (Jgatsiz.)
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 flamdula 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-

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 planulae, 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 Cyanese, however, when adult, are usually found
singly, while the Aurelige, on the contrary, seek each other, and
commonly herd together.

Fig. 50. Aurelia flavidula, seen from above ; o mouth, e e e e eyes, mm mm lobes of the mouth,
oooo 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.
Fig. 62.

Campanella seen in profile ; greatly magnified.
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. (Trachynema 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.

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
Fig 54 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 Lucernaria; attached to eel-grass ; natural size.

LUCERNAEIA. 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 thes-e
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

HYDROIDS.

J^ California

S^E^^~^_ ,-—

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
Medusas 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 Siphonophoraa, 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.

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 Medusa3 developed one below the
other ; when ready to hatch, the calycle bursts and allows them
to escape.

Eucope. (Eucope diaphana 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.

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. 81. 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 r" rases 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 planulae, 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. Fig. 66. t>

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 011 each side of base of tentacles.

54 MARINE ANIMALS OF MASSACHUSETTS BAY.

state, forming slight projections at the 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.

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 on 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
rig 69 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.
Iii 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

Vlg. 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.

water 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 j 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,
Fjg 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 Medusse 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 tentacles. ( A</a**ig.)

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 planulae, 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.

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 Medusae
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 planulae just attached to the ground.

Fig. 83. Young Hydrarium developed from planulaj ; magnified.

66 MARINE ANIMALS OF MASSACHUSETTS BAF.

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 Hydrae 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-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 (Dyphasia 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
on the stock, never becoming free. The free Medusas 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 Lafcea. Fig. 87 repre-
sents one of these young Sertularian Medusae (Lafoea cornuta
Larnx.).

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 Lafrea.

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 mirabilis 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. 90.

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. (Agassiz.)

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

SARSIA.

69

Fig 91.

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
Medusae 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-
sas. In Fig. 91 we have one of the
Tubularian Medusae (Turris 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.

Bougainvillia. (Bougainvillia 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 5 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.

Fig. 93.

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.

BOUGAINVILLIA.

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. 9? 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 llydroid ; 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 Coutliouyi 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.

m \\

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. (Jtgajisiz.)

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

HYDRACTINIA.

Hydr actinia. (Hydractinia polyclina AG.)

This is another Tubularian, covering the surface of rocks ill
tide-pools, or attaching itself upon shells inhabited by hermit
crabs. Indeed it was iipon 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 Medusae ; 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 Medusas, 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 ;
0 globular tentacles, t slender tentacles of sterile individual. (Agassis.)
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 •, r o chymiferous tubes, v proboscis, s circular

tube, m young Medusas at base of long tentacle t. (Agassiz.}

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

Medusae at base of long tentacle t. (JJgassiz.}

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

(Agassiz.)

DYSMORPHOSA. 75

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
Couthouyi, 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. (Dysmorpliosa 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-
dusas, viz. that of budding from the proboscis. One of our most
common little Jelly-fishes, the Dysmorpliosa (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 5 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 Medusa 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 Siphonophorae.

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-

Fig. 107. Fig. 108. • , . , , . ~ . ,

ity ; it has, in fact, but one organ,
and one function, and consists of
an alimentary sac resembling the
probo*scis 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 Medusae.

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. 110.

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. 108.

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

78 MARINE ANIMALS OF MASSACHUSETTS BA?.

Besides these locomotive members, the community contains three
kinds of Hydras 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 ul 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 Hydrae 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.

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-
Fig. 114. ce^s are scattered at uneven distances (Fig. 114).
The special function of these closed Hydrae 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 Medusae 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

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 Nanomia, 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 no 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 Hydras, 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 Hydrae 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 iipper 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, (fee., 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 Arethma 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
Hydrae (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 ;

Fig. 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 tlicir 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. 113.

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 noi
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 Hydroids.

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

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

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

Fig. 121. Free Medusas of Velella ; a proboscis, b chymiferous tube, c circular tube. (Ayassiz.}

MODE OF CATCHING- JELLY-FISHES. 85

MODE OF CATCHING JELLY-FISHES.

NOT the least attractive featiire 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, <fcc., the other for the smaller fry, such as the various
kinds of Ctenophorse, the Tima, Melicertum, &c. 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-
weecjs, 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 Medusas 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, &c., 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 ; 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 Saunders'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 Aureliae and Zygodactylae 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, &c., 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

California-

* -,-.
OUR illustrations and descriptions of Echinoderms 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 Echinoderms. 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 Echinoderms 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
Echinoderms 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 Echinoderms 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 Echinoderms, 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 interambulacral
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-
terambulacral 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 svstems 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

HOLOTHURIANS.

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 Ctenophoraa, 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 tiirned 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 nutritioiis 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 j greatly mag-
nified.

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 Synaptae, 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. (Caudina arenata STIMPS.)

Several other Holothurians are frequently met with on our
shores. Among them is the Caudina arenata (Fig. 126), a
small Holotlmrian, 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 Holothurian 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 Holpthurians 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, g1 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 5 expanded about one third the natural size.

ECHINOIDS. 101

only ill 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.

ECHINOIDS.

Sea-urchin. (Toxopneu&tes 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. ' Tliese 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,

Fig. 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 mouth, the ten zones diverge, curving upward to meet in the
dorsal area on the summit of the body. (Fig. 133.)

Fig. 132. Fig. 133.

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 on 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. (Ayassiz.)

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.

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

Fijr. 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 pedicellariae ; 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 pedicellariae 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 ; s stem, p base of fork, t fork.

14

106 MARINE ANIMALS OF MASSACHUSETTS BAY.

away of the refuse matters ; nor do the 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
138- with a complicated intestine, which extends

spirally from the lower to the upper floor of
the body, festooning itself from one ambula-
cral 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 sustain the teeth, being made up of a
number of pieces, and moved by a complicated
system of muscular 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.

Echinarachnius. (EcMnarachnius 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 5 a acabulacral zone,
i interambulacral zone.

108

MARINE ANIMALS OF MASSACHUSETTS BAY.

FIR. 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
biiilt 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
(0, 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 Vertebrates,, or from right to left like those of Articu-
lates, move concentrically, all converging towards the centre.

STAR-FISHES.

Star-fish. (Astracanthion 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 ambulacral ramifica-
tions, ww interamhulacra. (JJgassiz.)

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 pedicellariae 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. (Ayassiz.)

110 MARINE ANIMALS OF MASSACHUSETTS BAY.

(Fig. 143), around which the pedicellarise 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.
Fijy. 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.

Fit? 148.

(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 Cribrellae
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 ; 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 be 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.

Hippasteria. (Hippasteria phryyiana 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.

CtenodiSCUS. (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 freqiients 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.

OPHIUKANS.

Ophiopholis. (Ophiopholis bellis 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 Arnphiura, 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, but are covered with little
warts or tubercles (Fig. 150) ; they are their locomotive ap-

Fig. 149.

Fig. 150.

pendages, and 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 5 magnified.

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
Nan tucket (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 be called (in regard of what hath
been before mentioned of it) a Basket-Fish, or a Net-Fish, 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 Ophi-
urans, the true Star-fishes, and the Sea-urchins ; and so promi-
nently were their prophetic characters developed, that mlany 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

m

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, where 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

ifi

Fig. 152. Foesil Pentacrinua.

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 Comatulae attached to
parent.
Fig. 154. Magnified view of the group of young Comatulae of Fig. 153.

EMBRYOLOGY OF ECH1NODERMS. 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
Comatulae, 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 (?/) 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
anus 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 opoiud 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-fah. (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, (d, 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.

EMBRYOLOGV 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.

tive cavity, two lappets, or little pouches, project (ww',Y\g. 101) ;
they shortly become completely separated from it, and form two
distinct hollow cavities (ww1, Fig. 162). 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 (£, Fig. 163).
Almost until the end of its growth, these two surfaces, as we

Fig. 158. Larva just hatched from egg 5 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, v vibratile chord, m mouth.

Fig. 163. Profile view of larva; b madreporic opening, w' earlet, ad digestive system, m mouth,
V v' 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 bnilt 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 (m, 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 oesophagus lead-
ing directly from the mouth (m) to the
second cavity or stomach (cf), which
opens in its turn into the third cavity,
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.

the alimentary canal.

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

EMBRYOLOGY OF ECHIN01IERMS.

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

Vis- 166.

two water-tubes above mentioned (w')» at the end nearest the di-
gestive cavity, a number of lobes are formed (£, 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

Fi? 166. Adult Larva, so-called Brachiolaria, lettering as before ; r back of young Star-fish, t ten-
tack-s of young Star-fish, //' bracliiolar 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
as suckers, and are placed just
above the mouth. As soon as
the Star-fish has thus secured
itself, it begins to resorb the
whole external structure de-
scribed above ; the water-tubes,
*4 the plastrons, and the compli-
cated system of arms connected
with 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 before.

EMBRYOLOGY OF ECIflNODERMS.

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 (m), around which

Fig. 168. Fig. 170.

the tentacles (f) 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. 168. 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

rig. 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 5 m mouth, b madreporic body, e, eye-speck.

Fig. 172. Young Star-fish seen in profile ; t' odd tentacle at extremity of arm.

Figs. 173, 174, 175. Young larvie of Toxopneustes in different stages of development ; e'-elv arms,
v-v" vibratile chord, ww' earlets (water-tubes), aod 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 ECfflNODEBMS.

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

Fig. 177. 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. 180.

Fig. 181.

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

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

EMBRYOLOGY OF ECHINODERMS. 135

Ophiurans.

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 in Fig. 183.

136 MARINE ANIMALS OF MASSACHUSETTS BAY.

Fig. 183.

Fig. 183. Larva of Ophiuran ; e1 - eiv arms, r' riv solid rods, v v' vibratile chord, iv w' water system,
b madreporic body, 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

Fig. 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 BAT.

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 are 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 type 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 ambulacra! 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 upon 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 Echinoderms. 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

DISTRIBUTION 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, <fcc., 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
faunae 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 Gorgoniae,
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 Cape
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
in5 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 (Scarus), 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 Algae 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 OP 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 t^e
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. — MADREPORIA AG.

Astrangia Dance AG.

ORDER HI.— HALCYONARIA EDW.

Halcyonium carneum AG.

CLASS II. — ACALEPH.S.

ORDER I. — HYDROIDEA JOHNST.

Velella mutica Bosc.
Phy salia Areihusa TIL.
Nanomia cam A. AG.
Millepora alcicornis LIN.
Hydractinia polyclina AG.
Tubularia Couihouyi AG.
Hybocodon prolifer AG.
Coryne mirabilis AG.
Turris vesicaria A. AG.
Bougainvillia superciliaris AG.
Dysmorphosa fulgurans A. AG.
Dynamena pumila LAMX.
Dyphasia rosacea AG.
Lafxa cornuta LAMX.
Melicertum carnjprfula PER. et LES.
Ptychogena lactea 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 LE8.

ORDER HI— CTENOPHOR^ ESCH.

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

SYSTEMATIC TABLE.

153

CLASS III.-ECHINODERMATA.

ORDER I. — CRINOIDEA.

Pentacrinus.

Alecto EschricTitii M. & T.

Alecto meridionalis AG.

ORDER H. — OPHIURIDEA.

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

ORDER III. — ASTERIDEA.

Ctenodiscus cr'ispatus D. & K.
Hippasteria pliryyiana AG.
Cribrella oculata FORBES.

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

ORDER IV. — ECHINIDE.A-

Toxopneustes drobachiensis AG.
Echinaraclmius parma GRAY.

ORDER V. — PIOLOTHURIDEA.

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

20

INDEX.

PAGE

Acalephs, 21

Actinia, 7

Actinoids, 7

Aleeto Eschrichtii, 121

Alecto meridionals, 121

Amphiura squamata, 115

Arachnactis brachiolata, 14

Astracanthion berylinus, 108

Astracanthion pallidus, 112

Astrangia Danse, 16

Astrophyton Agassizii, 117

Aurelia flavidula, 42

Bicidium parasiticura, 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, 112

Crinoids, 120

Crossaster papposa, 114

Ctenodiscus crispatus, 113

Ctenophorae, 26

Cuvieria squamata, 98

Cyanea arctica, 38
Development of Melicertum, 64

" " Tima, 64

Discophorae, 37
Distribution of Life in the

Ocean,
Dynamena pumila,

PAGE

Dyphasia rosacea, 67

Dysmorphosa fulgurans, 75

Echinarachnius parma, 106

Echinoderms, 91

Echinoids, 101

Embryology of Astracanthion, 1 24

" " Ctenophoraj, 34

" " Echinoderms, 123

" " Ophiurans, 135

" " Sea-urchins, 130

" " Star-fishes, 124

Eucope diaphana, 50

Halcampa albida, 16

Halcyonium carneum, 19

Halcyonoids, 1 9

Halyclistus auricula, 46

Hippasteria phrygiana, 113

Holothurians, 95

Hybocodon prolifer, 74

Hydractinia polyclina, 73

Hydroids, 49

Idyia roseola, 32

Lafoea cornuta, 6 7

Laomedea amphora, 65

Lucernaria, 46

Madreporians, 16

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, 115

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.

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