FLUSTRAD^. 



15 



Family IY. Bicellariad^. 



Bicellaria (De BL). Cells top-shaped, distinct, 

 armed with spines ; aperture looking upwards. 

 B. ciliata. Fig. 21 ; n.s. and mag. 



Bugiila (Oken). Cells elliptical, closely con- 

 tiguous, in two or more rows ; aperture very- 

 large ; margin simple, not thickened ; birds'-heads 

 (generally present) stalked and jointed. 



B. neritina. B. plumosa. 



flabellata. Murrayana. 



avicularia. Fig. 22 ; n.s. and mag. 



23 



Family V. Flustrad^. 



Flustra (Linn.). Cells contiguous, on both sides 



of the expansion. 



F. foliacea, F. truncata. 



papyracea. Fig. 23 ; n. s. and mag. 



Carhasea (Gray). Cells contiguous, on one side 

 only. 



C. papyrea. Fig. 24 ; n. s. and mag. 



