POLYZOA HYPPOCREPIA. 



PoLYPiARiA HYPPOCREPIA, P. Gervais in Ann. des Sc. Nat. vii. (1837) p. 77. — 

 PoLYZOA HYPPOCREPIA, J. E. Gray in Syn. Brit. Mus. (1842) p. 135. — LiM- 

 NiADES, Johns. Brit. Zooph. 248. AUman in Ann. and Mag. N. Hist. xiii. 



The organization of the polypes of this order is essentially 

 the same as that of the Polyzoa infnndibulata ; but the circle 

 of tentacula around the mouth is interrupted, in most of them, 

 on one side, so that they form a horse-shoe shaped group. 

 The distinction of sexes in the individuals is also more dis- 

 tinctly proved ; and the ova are not only not ciliated, but 

 they have a distinct envelope or shell. 



I follow Professor AUman in the arrangement and definition 

 of the genera. The following is a synopsis of them : — 



Polype-mass floating. CRISTA TELLID^. 



One genus only .... Cristatella. 



Polype-mass rooted. 



Massive or confervoid, inarticulate. PL UMA TELLIDJ^. 

 Massive and sponge-like . . . Aloyonella. 

 Confervoid 



Tentacular disc crescentic. . Plumatella. 



„ „ orbicular . . Fredericella. 



Confervoid, j ointed. PAL UDICELLA IDxE. 



One genus only Paludicella. 



