SYSTEMATIC 



CONCHOLOGT. 



Class CEPHALOPODA. 



Head large, connected with the body by a neck, and furnished 

 with complex, sessile or pedunculated eyes ; mouth with a pair 

 of mandibles or beaks, resembling those of a parrot, edged with 

 fleshy lips, and surrounded by a circle of arms. 



As pointed out in the structural portion of this work, the 

 Cephalopoda are related to the vertebrata in several j)artieulars : 

 in the mode of segmentation of the vitellus, in their internal carti- 

 laginous support — a simplified skeleton ; in their circulation fur- 

 nished with true capillaries, their blood corpuscles, their more 

 highly developed eyes, mandibles, etc. 



Differing from other mollusks by their symmetry as well as in 

 the above details, they nevertheless present, with more or less 

 modification, the main distinctive features common to other 

 classes of the subkingdom Mollusca. 



The Cephalopoda are essentially carnivorous ; their nourish- 

 ment is derived from fish, the migrations of which they follow, 

 and from pteropod mollusca. Certain sedentary species eat 

 crustaceans, nudibranchiate and bivalve mollusks and bryozoa. 

 After their exclusion, the j^oung prey upon polyps, notably on 

 those of the family Gorgonidse, so common on the Algerine 

 coast, and some of which, perhaps, furnish the material necessary 

 for the growth or solidification of the cuttle-bone. A little larger, 

 they attack with avidity those elegant chaplets of pearls, the 

 rainbow-hued eggs of Eolis and Doris. 



The number of cephalopods of small size is exceedingly great, 

 but they become the prey of a multitude of enemies. On the 

 10th Jan., 1858, the Dutch ship VriendentroAiw sailed for two 

 hours through dead Loligos, covering the surface of the sea as 

 far as the eye of the lookout could reach. Mr. Vrolik found in 

 the stomach of a Hyperoodon about ten thousand mandibles of 

 Loligo. 



