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POPULAR . SCIENCE REVIEW. 
anus in the middle line behind. On each side five small and 
similar buds appear, and these become ultimately the eight 
arms and the two tentacles. After a little time the essential 
similarity of the cuttle-fish to other nearly allied forms, such 
as the whelk or snail, becomes more evident as the body is 
more and more elevated above the egg. Then, while the 
embryo is still only bilaterally symmetrical, it is plainly to be 
seen that the incipient arms are nothing more than external 
outgrowths from, and prolongations of, that organ on which the 
whelk, snail and such creatures walk, viz. the foot, while the fold 
on each side above the incipient arms, and which is ultimately 
to become half the funnel, is seen to answer to a similarly 
placed expansion in certain exceptionally-formed creatures 
allied to the whelk, and which expansions have been named 
epipodia. 
As development goes on, the mouth is gradually brought 
into the centre of the radiating arms, which increase greatly in 
length, while the body mounts higher and higher, the pallial 
chamber gradually assumes its permanent form, the two halves 
of the syphon unite, and the intestine becomes convoluted, &c. 
Such is a short account of the more salient points in the 
structure of the cuttle-fish, which is a nocturnal marine animal 
preying on fishes, lobsters, and other sea-dwelling animals, 
which it seizes in its wonderfully tenacious grasp, while it 
tears them to pieces with its powerful horny jaws. 
The cuttle-fish is interesting, because it presents us with the 
most fully developed and complex condition of that type of 
structure to which it belongs. All snails, slugs, whelks, limpets, 
periwinkles, pteropods,* the argonaut, the nautilus, the extinct 
ammonites and belemnites, &c., all pretty closely resemble the 
cuttle-fish in structure ; while even all oysters, cockles, mussels, 
and the exceedingly numerous other creatures of that kind 
belong to the same essential type as does the cuttle-fish ; the 
whole of the above enumerated forms, with their allies, con- 
stituting one great primary division of the animal kingdom 
called AIollusca, just as all the creatures similarly allied to 
the lobster constitute another such great primary division 
termed Annulosa. 
A few words must be said, however, about some of the above- 
mentioned forms which most closely resemble the cuttle-fish in 
build, and are on that account associated with it in a subordi- 
nate group termed a chiss, and to which class the name Cepha- 
lopocLa has been applied, on account of the aggregation of the 
• These nre small, free, surface-swimming creatures, which abound in 
myriads on the surface of the open ocean, both in hot and in cold latitudes, 
n the latter they fonn the principal food of the whale. 
