NAUTILUS SAILOR. 137 



itself within its boat, draws in water, and imme- 

 diately disappears. Though capable of float- 

 ing on the surface of the sea, it is often found 

 reversed, and like a snail bearing its house upon 

 its back. The name is derived from the Greek 

 word vavnXos (nautilos) a sailor. 



The animals inhabiting the shells of this and 

 the following genus vary considerably from the 

 other mollusca ; they are called Cephalopodes,* 

 (footed at the head,) because their heads are 

 surrounded by arms or tentacula. Their 

 bodies are fleshy like the other mollusca, and 

 the posterior portion is contained in the mantle 

 of the animal. The mouth is vertical and 

 armed with two corneous mandibles resembling 

 the beak of a parrot. They live in the sea, 

 are carnivorous, and feed on crabs and other 

 marine animals. The position of their arms 

 enables them to seize their prey, and bring it to 

 their mouth. The Cephalopodes which form a 

 multilocular shell, instead of being enclosed 

 within it, envelop it so as only to leave a small 

 portion visible : a tendinous thread which issues 

 from the extremity of the body appears to attach 

 the latter to the shell, it probably has some con- 

 nection with the siphunculus. 



As in the genus Teredo we observed how 

 extensive a work of destruction is carried on by 

 a little worm, here we have to notice the reverse 



Cephalopodes. Having feet on the head, from the Greek 

 (cephale) a head, and nodes (podes) feet. 



