J3ELEMNITES. 



261 



an internal coiled shell. The shells of Spirula Peronii La- 

 marck are rarely thrown ashore on Nantucket ; it lives upon 



Fig. 217. Pearly Nautilus, N. pompilius. Seen in section showing 

 the chambers and siphuncle. Half natural size. From Tenney's Zo- 

 ology. 



the high seas. The extinct Belemnites had, like the recent 

 Moroteuthis Verrill, a straight conical shell, the "thunder- 



. 218. Poulpe or Common Octopus of Brazilian Coast. 



bolt" fossil. Allied to Loligo and Ommastrephes, are gigan- 

 tic cuttle-fishes which live in mid-ocean, but whose remains 



