CHAPTER XV. 



OF THE CLASS OF CEPHALOPODA. 



877. THE Cephalopoda unquestionably constitute the group 

 of highest organisation in the Molluscous sub-kingdom. They 

 are characterised by the possession offset, or locomotive organs, 

 around the head ; whence their name is derived. But these feet 

 have no analogy either with the fleshy disc of the Gasteropods, 

 or with the feet of Articulata or Vertebrata. They are, in fact, 

 prolonged tentacula, or lips. In the Nautilus (Fig. 548), which 

 approaches the nearest to Gasteropoda, they are very numerous, 

 and are evidently feeble as instruments of prehension ; whilst 

 they would seem, from the distribution of their nerves, to be 

 more concerned in sensation. On the other hand, this animal 

 possesses a single fleshy disc, evidently analogous to that of the 

 Gasteropods, on which it probably crawls, when moving along a 

 solid surface, in a position analogous to theirs. In some of the 

 Cephalopoda the feet are much prolonged, and of great power ; 

 and are evidently very important organs both of locomotion and 

 prehension (Fig. 543). But in those forms which approach 

 most nearly to Fishes, we find them again reduced in size, very 

 much in proportion to the elongation of the body ; and it is by 

 the latter, and the fin-like expansions with which it is provided, 



that progression is then 

 chiefly accomplished (Fig. 

 540). There are Fishes 

 which possess tentacular 

 F,G.540.-CALAMARY. prolongations of the lips, 



which are evidently analogous to the arms of the Cephalopoda ; 

 and this is one among the many interesting points, by which a 

 transition is effected between these two classes. The Nautilus 

 is the only one amongst existing Cephalopoda, in which the prin- 



