MOLLUSCA. 63 



shells of the nautilus were used in early times as drink- 

 ing cups, ornamented with various devices, and found in 

 all large assemblies. Little is known concerning the 

 habits of the nautilus. 



The larger species of the cuttle fish race in early 

 times were objects of dread to the ancient mariners, and 

 are the foundation for all the marvelous stories of the 

 Kraken, which is represented as a gigantic mollusk, 

 that could grasp a ship in its long arms, and drag it to 

 the bottom. The Ammonites (snake-stones), Bdcm- 

 nites (thunder-stones nautilata), now only found in a 

 fossil state, belonged also to the class of cephalapoda. 



SECOND ORD ER. 

 GASTEROPODA. 



Mollusca of this class crawl by means of a fleshy mass 

 which covers the lower surface of the abdomen ; the back 

 is furnished with a mantle, which can be more or less 

 extended or compressed, and is of various forms, but 

 mostly assumes that of a spirally- twisted shell. The 

 head is plainly developed, and in most appears to be very 

 strong ; the mouth is surrounded with feelers, which 

 they are constantly using ; the eyes are very small, and, 

 in some, entirely wanting.* The calcareous envelope, 

 which is formed by the enclosing mantle, increases in 

 size every year, and more or less resembles a spirally- 



* Many of these animals are entirely naked ; others Lave an inter- 

 nal shell concealed in the thickness of the mantle ; but most of them 

 have an external shell, -which is almost always sufficient to contain 

 them entirely and afford them protection. NAT. PHIL. Tr. 



