S44; lOOIiOGY. 



ORDER II. 



MOLLUSCA. 



The bodies of all this order are simple, and furnished with 

 limbs ; many of them are destitute of any coat or covering, 

 some are quite gelatinous, and others furnished with a crust 

 or shell, which differs in substance from the shells of Testa- 

 ceous Animals, the latter being principally composed of car- 

 bonate of lime, and those of Crustaceous Animals, of phos- 

 phate of lime. But few of them are applicable to the uses 

 of Mankind. There are thirty-two genera in the order. 



* Mouthplaced above. 



1. Actinia. Body fixed, with a single terminal dilatable 



aperture^ surrounded with tentacula or cirri. 



2. Clava. Body fixed, with a single vertical dilatable apcr- 



turey surrounded with clavate teniacula. 



3. Pedicellaria. Body fixed, and furnished with a rigid 



peduncle. 



3. Mammaria. Body not affixed, smooth, wit a single 

 aperture, without cirri. 



5. Ascidia. Body fixed, with two apertures, one of which 

 is terminal, the other situated a little beneath. 



