268 HISTORY OF BRITISH ZOOPHYTES. 



Polypidom crustaceous; cells in a single layer. 



Lepralia. 

 Polypidom crustaceous; cells quincuncial. Mem- 



BRANIPORA. 



Family V. Polypidoms multiform, composed of oblong 

 sub- quadrangular cells, disposed in semi -alternating 

 series ; the cells conjunct, horizontal to the plane of 

 axis, with a subterminal or lateral aperture, usually 

 covered with an ovarian capsule. Esciiarid.e. 

 Pol^l^idom foliaceous or membranous, composed of 

 several series of oblong sub -quadrangular cells, on 

 two planes, or one only. Plustra. 

 Polyj)idom membrano-calcareous, frondescent; the cells 

 immersed, in a double layer placed back to back, 

 like the cells in honey-comb. Esciiara. 

 Polypidom calcareous, frondescent, netted; the cells 



on the upper side only. Eetepora. 

 Polypidom dichotomous, with jointed cylindrical 

 branches; cells immersed, rhomboid. Salicornia. 

 ^^^^ Polypidoms sponge-like, fleshy, polymorphous ; the 

 cells irregular in disposition, immersed, with a con- 

 tractile aperture ; no external ovarian capsules. Hal- 

 CYONELLEA, Eh'oih. Corall. 153. 



