CHAPTER XXII. 



CEPHALOPODA. 



CLASS IV. CEPHALOPODA. The last and highest class of 

 the Mollusca is that of the Cephalopoda, comprising the 

 Cuttle-fishes, Calamaries, Squids, and the Pearly Nautilus. 

 They are all inhabitants of the sea, 

 and are all carnivorous ; and they are 

 possessed of considerable powers 

 of locomotion. At the bottom of 

 the sea they can walk about, head 

 downward, by means of the arms 

 (Fig. 89), which surround the 

 mouth, which are usually provided 

 with numerous suckers, and which 

 are really produced by a splitting 

 up of the margin of the foot. It is 

 from the presence of these arms 

 that the class derives its name (Gr. 

 Jcephale, head ; and joocfes, feet). The 

 Cuttle-fishes can also swim rapid- 

 ly, either by means of expansions 

 of the skin constituting fins, or by 

 the forcible expulsion of water 

 from the cavity of the mantle, the 

 reaction of which causes the animal 

 to move in the opposite direction. 

 The majority of the living Cephalo- 

 pods are naked, possessing only an 

 internal skeleton, and this often a 



rudimentary one ; but the Argonaut (Paper Nautilus) and the 



an external shell, though 

 Ferent in the two forms. 



8d ,_ S epioia Atlanta, one of 

 the Cuttle- fishes (after Wood- 



A Ui.VAJLU.A\_/JJLL/C**l UUW IJIAV LM.J.Vy UUf&VrUCVW 



Pearly Nautilus are protected by 

 the nature of this is extremely diffe 



