293 



MANUAL OF ZOOLOGY 



tion, and surrounds the mouth. A distinct head is pres- 

 ent, and the foot assumes the appearance of a system of 

 appendages of the head. In the cuttle-fishes (Fig. 182), 



jaws inf 



cart 



Tnank 



ruLd- 



mus, 



7r1a.nl '- 



Fig. 183. — Nautilus pompilius, diagrammatic lateral view of a female specimen 

 enclosed in its shell, cart, cartilage; ctt;t, ctenidia; hd, hood; inf, funnel; 

 jaws, jaws; mant, mantle: mant' , dorsal mantle-fold overlapping the coil of the 

 shell; mus, position of lateral mass of muscle; nid, nidamental glands; sept, 

 first septum; siph, siphuncle. (After Keferstein.) 



squids (Fig. 187), Octopi, and Argonauts (constituting the 

 sub-class Dibranchiata) the main part of the foot is composed 



