6 
THE NEW YORE AQUARIUM JOURNAL. 
BUTTERFLIES OF THE SEA. 
Although it is intended that the New York 
Aquarium shall be the most complete in the 
world as respects the beauty, rarity and variety 
of the forms of marine lile there exhibited, yet 
there will still remain many wonders of the 
great sea which it will be impossible to capture 
and confine. This being the case it is the pur¬ 
pose of the conductors t>f 
this journal to resort to 
lustrated descriptions where 
the actual lriing object is 
not to be obtained. With 
this object in view' and as 
the first of a series of kin¬ 
dred articles, the attention 
of our readers is directed 
to a small but important 
group of mulluscs bearing 
the technical name Ptero- 
poda or, wing-footed mol¬ 
luscs, but to v'hich the 
more popular term of But¬ 
terflies of the Sea has also 
been given. 
A recent writer gives us 
the following interesting 
description of these strange 
creatures, and this account 
is rendered the more attrac¬ 
tive by the carefully chos¬ 
en illustration which we 
have added. We are told that 
away in the far north of the 
Arctic regions, floating in 
myriads upon the surface 
of the northern seas, and 
constituting vast fields ol 
life, through which ships 
may sail for days and nights 
together,"~are Foilnd mul¬ 
titudes of small animals, 
to which the appropriate n a me of “butterflies 
oi the sea ” has been given. To watch one 
of these beings, persuing its way through the 
waters by means of two wing-like appendages 
springing from the sides of the neck, and to note 
the delicate body, inclosed in some cases in a 
delicate glassy shell, the comparison or resem¬ 
blance to the aerial insect is by no means far¬ 
fetched or strained. And in their organization 
and habits, these little organisms may be found 
to present some points of great interest to the 
non-technical reader; whilst to the naturalist 
they have ever afforded subjects of pleasant study 
and instruction. 
The position of the sea-butterflies in the ani¬ 
mal scale is ol sufficiently well-determined kind. 
They are molluscous animals, that is, are allied 
to our ordinary shell-fish, such as oysters, mus¬ 
sels, &c., as well as to cuttle-fishes and allied 
beings. Their nearest relations are undoubt¬ 
edly^ the whelks, cowries, and other shell-fish, 
belonging to the great molluscan class known 
to naturalists as the Gasteropoda ; and whilst 
some naturalists regard the sea-butterflies as 
orming a distinct group of themselves, others, 
and with every show of reason, maintain that 
they should be placed merely as a branch of the 
Gasteropod class. The scientific appellation of 
our sea-butterflies is the Ptefopoda —a name sig¬ 
nifying “wing-footed," and which is thus of 
expressive enough kind, when we consider the 
manner in which they flit over the watery wastes. 
Besides being able to swim quickly and well 
by aid..of their wing-like fins, the sea-butterflies 
can descend into the ocean-depths, or ascend 
from these depths to the surface, at will. They 
appear further to come to the surface chiefly at 
night or in the twilight; and as a naturalist has 
well remarked, each species or kind of these ani¬ 
mals seems to have its own and special degree of 
darkness in which it ascends from the depths. 
Thus, did we know sufficient of the history of 
these little animals, we might be able to construct 
a Pteropod-clock by watching the respective hours 
of their appearance at the surface of the sea ; just 
as the botanist forms a ‘ floral clock' by watching 
the times of the opening and closing 61 flowers. 
Being ‘ shell-fish,’ the Pteropods usually pos¬ 
sess a shell; this latter structure, it must however 
be noted, not being developed in all these beings. 
A very beautiful, and at the same time most rep¬ 
resentative kind of sea-butterfly, is that known by 
the name of the Hyalcea ., of which kind there are 
several distinct species; and in this form, as well 
as in another well-known species called Cleodora, 
a shell is developed, The shell is thus seen to 
consist of a very delicate glassy structure, some¬ 
what triangular in shape, and of elongated form in 
Cleodora ; that of Plyalsea being composed of 
two plates united together, and forming a small 
shell of elongated or globular shape. The little 
head extremity ot the animal, provided with its 
‘ wings,’ protrudes in each case from the front or 
open extremity of the shell. Another very famil¬ 
iar sea-butterfly is the Clio, which does not pos¬ 
sess a shell, but appears as a little oblong body 
about an inch in length, and terminating in a 
lower pointed extremity. 
No part of the structure of the sea butterflies 
presents more surprising details than that ol the 
head and its appendages ; the latter consisting of 
tentacles, jaws, and like apparatus, exercising the 
sense of touch and other offices. Thus, on each 
side of the mouth of Clio, we discover three 
fleshy appendages, which at first sight might ap¬ 
pear to consist of simple tentacles or organs of 
touch. When, however, we bring the microscope 
to bear upon these bodies, we note the interesting- 
fact, that the surface of each is literally studded 
over with numerous minute specks, which, when 
more fully magnified, are seen to be of hollow 
cylindrical shape, and to contain, each about 
twenty little suckers. These suckers may be pro¬ 
truded at will from their respective cylinders, so 
as to constitute an efficient apparatus for seizing 
and detaining particles of food. Thus if we con¬ 
sider that each of the six tenacles bears, on an 
average, about three thousand of the cylindrical 
bodies, and that each of the latter in turn con¬ 
tains about twenty suckers, we reach the enormous 
numbei of three hundred and sixty thousand 
suckers, as constituting the prehensile armament 
of a single Clio, itself of very small size. And 
imagination may assist us in its scientific aspects 
better than any other intellectual process, in 
endeavoring to form some idea of the extreme 
delicacy of the muscles and structures whereby the 
protrusion and retraction of the suckers are secured. 
Two fleshy ‘hoods’ serve to inclose the tenta¬ 
cles when the latter are not in use and are re¬ 
tracted ; and other filaments exist which may be 
used to subserve the sense of touch in these forms. 
Within the little mouth of the sea-butterflies, as 
also well exemplified in Clio, peculiar jaws and a 
curious ‘ tongue ’ exist, for 
the mastication of food. 
Each jaw is a conical struc¬ 
ture, which literally bristles 
with sharp spiny teetli; and 
the ‘tongue’ is likewise stud¬ 
ded over with recurved 
hooks, which also aid in 
rasping down or triturating 
the nutrient matters. And 
as completing the alimentary 
apparatus of the sea-butter¬ 
flies, we find a well-devel¬ 
oped threat, stomach, a large 
liver, salivary glands, and 
other addenda; whilst a 
heart is also present, along 
with a system of blood-ves¬ 
sels for the conveyance of the 
vital fluid through the body. 
The breathing organs in 
some of these beings are well 
developed, and appear in the 
form of delicate gills, or 
analogous structures, which 
are sometimes, as in Ply- 
alaea, inclosed within a spe¬ 
cial chamber, but in others, 
such as Clio, are apparently 
unprqtected, and of indis¬ 
tinct nature. 
A very large ‘ brain/ —or 
at anyfatea mass of nervous 
matter corresponding in 
function to thegreat nerve-centre of higher animals 
—is developed in the sea-butterflies, and can be 
discerned lying beneath the throat, and forming, 
in fact, a kind of internal collar around the gullet. 
And nerves accordingly radiate throughout the 
body from thisc entral mass, and supply the various 
parts of the organism with feeling and vital Jfower. 
Especially, as we might expect, do v r e find the del¬ 
icate tentacles of the head to receive a large nerve- 
supply ; and we may also note the presence of txvo 
eyes, situated on the back of the neck. These latter 
organs are not of a very high order of development, 
but doubtless subserve the function of guiding 
their possessors in their marine flights. 
The food of our sea-butterflies appears to consist 
of the more minute marine‘Crustacea, which with 
themselves, haunt the surface of the sea. Thus 
tlrese small beings exist on organisms of still lesser 
magnitude. But in turn the sea-butterflies form a 
large proportion of the food ol the largest of ani¬ 
mals—the whales themselves. Drawn in myriads 
into the capacious mouth of the Greenland whale, 
with the floods of water which thegreat monster of 
the deep from time to time imbibes, the sea-butter¬ 
flies remain entangled in the ‘baleen’ or whale¬ 
bone plates of the jaws, and are thereafter swal¬ 
lowed as nutriment; and the species Clio Borealis, 
from this latter circumstance, becomes known to 
us under the popular name of ‘whales’ food.’ 
Sea-birds also prey upon the butterflies of the 
ocean, which thus contribute largely to the sup¬ 
port of much higher forms than themselves. In 
the Mediterranean Sea, on the Australian coasts, 
and in the Atlantic Ocean, the sea-butterflies also 
occur, but not in such numbers as in the far north, 
whither, to the very home of the Pteropods, 
modern enterprise has advanced on a noble mission 
of discovery. 
Small as are all the existing representatives ot 
the sea-butterflies, it may prove interesting to note 
in the last place, that, in past epochs of this world’s 
history, several relatively gigantic members of this 
class appear to have been developed. Insome 
CARTNA'RTA. Car'mrrG Meditrrrinya. 
HTALEA .-llyaLa IrULmaui. (Empty slifcll below.) oV.UfiULIA .— Cymlmlia Peronii. 
CLEODORA .—Cleodora pyramidata, 
SPIKE-SHELL .—Creseis aciculata. 
