POLYZOA HYPPOCREPIA. 



POLYPIARIA HYPPOCIIEPIA, P. Gervais in Ann. des Sc. Nat. vii. (1837) p. 77. 

 POLYZOA HYPPOCREPIA, ./. E. Gray in Syn. Brit. Mus. (1842) p. 135. LIM- 

 NIADES, Johns. Brit. Zooph. 248. Allman in Ann. and Mag. N. Hist. xiii. 



The organization of the polypes of this order is essentially 

 the same as that of the Polyzoa iufundibulata ; 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 Allman in the arrangement and definition 

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



Polype-mass floating. CRIST A TELLID^E. 



One genus only .... CKISTATELLA. 



Polype-mass rooted. 



Massive or confervoid, inarticulate. PL UMA TELLID^E. 

 Massive and sponge-like . . . ALeroNELLA. 

 Confervoid 



Tentacular disc crescentic. . PLUMATELLA. 



orbicular . . FREDERICELLA. 



Confervoid, jointed. PA L UDICELLAID^. 



One genus only. . . . . PALUDICELLA. 



