APLIDIUM. 590 



Genus POLYCLINUM, Savigny. 



Test gelatinous or cartilaginous, polymorphous, sessile or 

 slightly pedunculate; systems numerous, convex, radiated, 

 each with a central cloacal cavity. Individuals placed at 

 unequal distances from a common centre ; abdomen much 

 smaller than thorax; post-abdomen pedunculate; branchial 

 orifice six- angled and six-rayed, anal prolonged horizontally 

 and irregularly cut. 



Ex. P. aurantium, Milne-Edwards, pi. 134, fig. 3. In- 

 dividual, P. aurantium, fig. 3, a. 



There are about seven species, inhabiting the shores of 

 Britain, the Mediterranean, the Red Sea, and India. 



Species of Pohjclinum. 



aurantium, Milne-Edw. isiacuru, Sav. 



constellatum, Sav. saturnium, Sav. 



cythereum, Sav. uranium, Sav. 

 hesperium, Sav. 



Genus APLIDIUM, Savigny. 



Test gelatinous or cartilaginous, sessile ; systems nume- 

 rous, prominent, without central cavities. Individuals placed 

 in single rows, at equal distances from the centres ; bran- 

 chial orifice six-rayed, anal simple, indistinct. 



Syn. Alcyonium, part, Auct. Polycitor, part, Renieri. 



Ex. A. fallax, Johnston, pi. 134, fig. 4. Individual, A. 

 lobatum, Saviyny, fig. 4, a. 



The species of Aplidium are usually found attached to 

 stones, &c, in deep water. They are met with on the coasts 

 of Europe and the Red Sea. 



