CHAP. II. THE CEPHALOPODA. 39 



of a radiated animal ; and the sides of the body are 

 either slightly dilated into a distinct fin-shaped mem- 

 brane, or are so thin that it can be used for the same 

 purpose. In size, the cuttlefish are by far the largest 

 of all the testaceous MoUusca ; they are, indeed, the 

 giants of invertebrated animals ; for, if the accounts of 

 the old Indian voyagers are true, there are some of 

 such enormous dimensions, that they seize upon the 

 divers, entangle them in the folds of their serpent-like 

 arms, and finally devour them. These stories are, no 

 doubt, exaggerated ; but we have, ourselves_, seeft many 

 of such a size, caught on the shores of Sicily, that two 

 would be a good load, — their arms being as thick as 

 those of a man. Most of these animals now in exist- 

 ence are naked ; but in the former aeras of the world, 

 there appears, unquestionably, to have been a most 

 numerous and gigantic race, which had a part of their 

 body protected by a spiral shell, rolled in the form of 

 a disk. Ancient revolutions of our globe, however, 

 have swept away nearly the whole of these testaceous 

 monsters, leaving in the Nautilus almost the only 

 genus hitherto found in a recent state. It is among 

 the existing genera that we find a horny or calcareous 

 plate, which supports the body, and is altogether in- 

 ternal. This, as before remarked, is the first indication 

 of the vertebrated structure among molluscous animals ; 

 and hence, nearly all zoologists place these animals 

 immediately in junction with the Vertehrata : or what 

 is the same thing, consider them the last in the series 

 of the MoUusca. It thus appears, on a general view of 

 the whole of the testaceous MoUusca, that they may be 

 thus concisely described : — The typical and sub-typical 

 divisions crawl, and are covered with calcareous shells ; 

 of which the first is univalve, and generally spiral, 

 while that of the other is bivalve and simple. The 

 aberrant group, on the contrary, have no calcareous 

 covering, but are externally naked, and they have the 

 faculty of swimming added to that of crawling. Thus, 

 we cannot but admire the simplicity and beauty of the 

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