266 HISTORY OF BRITISH ZOOPHYTES. 



II. Hypocrepia. Lacustrine or fresh-water. Polypes 

 compound; the mouth surrounded with ciliated retractile 

 tentacula, interrupted or depressed on one side, so as 

 to assume a crescentic or horse-shoe form : ova unci- 

 liated. — Dr. Johmton. 



I. POLYZOA INFUNDIBULATA. 



The families and genera are thus arranged : — 



* Polypidoms calcareous ; the cells tubular, with a round 

 terminal aperture, uncovered with an operculum. Tu- 



BULIPORINA. 



Family I. Polypidoms multiform, massive or crustaceous. 



TUBULIPORID^. 



Polypidom wart-like, with a defined base; the cells 

 sub-erect, aggregated, or imperfectly rowed. Tubu- 



LIPORA. 



Polypidom crustaceous, undefined; the cells horizontal, 



semi-alternate. Diastopora. 

 Polypidom erect, branched; the cells opening all round, 



semi-alternate or irregular. Pustulipora. 

 Polypidom dichotomous ; the segments free ; cells in 



alternating cross-rows on one surface. Idmonea. 



