MOLLUSCA. 211 



among the Zoophytes. They are compound animals, many 

 individuals united by a compound integument, and arranged 

 according to a uniform plan. 



In some cases, there is only one system of individuals in 

 the mass, in other cases, there are many similarly arranged 

 and contiguous. The tentacular filaments of the branchiae 

 appear to be distinct. They are destitute of the intestinal 

 rib which occurs in some of the preceding genera* 



1. Branchial Orifice Radiated. 



a. Branchial and anal orifices, with six rays. 



(A.) Body sessile. The angles of the branchial meshes 

 furnished with papillae. The thorax, or cavity containing 

 the branchiae, cylindrical* The abdomen is inferior, with a 

 stalk. Ovarium sessile, and single* 



GENUS DIAZONA. Body orbicular, with a single system 

 of animals disposed in concentric cirles. 



The substance is gelatinous. The ovarium enclosed in 

 fold of the intestine. D. violacea of Sav. tab. ii. f. 3. 



GENUS POLYZONA. Body polymorphous, with many sys- 

 tems disposed subcircularly. 



The body is subcartilaginous. The individuals are dis- 

 posed irregularly around the common centre. Savigny 

 inadvertently termed this genus Distoma, a name long 

 pre-occupied amongst the intestinal worms. The Alcyonium 

 rubrum of Plancus, and the Distomus variolosus of Gaert- 

 ner, belong to this genus. The last is a native species. 



(B.) Body pedunculated* 



GENUS SIGLLLINA. Body a solid cone, consisting of a 

 single system of many individuals, irregularly disposed, one 

 above the other. 



The thorax is short, and hemispherical. The angles of 

 the branchial meshes destitute of papillae. The abdomen 



