000 POLYCL1NIN/E. 



Species of Aplidium. 



chrystall inum, Eenieri. gibbosulum, Low. and KoUiker. 



fallax, Johnston. lobatum, Sav. 



ficus, Linn. nutans, Johnston. 



Genus SIDJSfYUM, Savigny. 



Test gelatinous, incmsting ; systems numerous, conical, 

 truncated and starred at the summit. Individuals arranged 

 round a depressed centre ; branchial orifice eight-toothed, 

 anal simple, tubular, folded against the thorax. Ovary 

 pedunculate. 



Ex. S. turbinatum, Savigny, pi. 134, fig. 5. Individual, 

 S. turbinatum, fig. 5, a. 



The animals of Sidnyum partake of the characters of 

 Synoicum and Aplidium, resembling the former in the 

 structure of their stomach, and the latter in their branchial 

 apparatus. Each has an eight-toothed branchial orifice, and 

 a simple tubular vent folded against the thorax. The ovary 

 is pedunculated, and very conspicuous at the extremity of 

 the animal. 



Genus synoicum, Phipps. 



Test semi-cartilaginous, cylindrical, pedunculate, isolated 

 or gregarious; systems single, circular, terminal. Indivi- 

 duals six to nine ; branchial orifice six-rayed, anal orifice with 

 six unequal rays, the largest three forming the outer margin 

 of the central star; post abdomen sessile. 



Ex. S. turgens, Phipps, pi. 134, fig. 6. Individual, S. 

 turgens, fig. 6, a. 



The only species of this genus at present known is from 

 the Arctic seas. 



