3°2 



MANUAL OF ZOOLOGY 



lamellae. In Loligo x (the squids) the shell (Fig. 187, B) is 

 long, narrow, and completely horny ; it corresponds to the 

 pro-ostracum, the phragmocone being entirely absent. 



Fig. 187. — Loligo vulgaris. A, entire animal, dorsal view; B, horny internal shell 

 or pen. (From Keferstein ) 



In Octopus the shell is represented only by a pair of 

 rudiments with which muscles are connected. In Argonauta 

 there is no shell in the male, but the female has an external 

 shell (Fig. 188) of a remarkable character. This is a deli- 



1 Our common American species is Loligo peahi. 



