378 Kev. T. Hincks's Contributions towards 



transversely across the front wall ; aperture subterminal, 

 occupying about one third of the whole length, with a mem- 

 branous covering, arched above, lower margin straight or 

 slightly curved outwards ; peristome thickened and often some- 

 what elevated at the sides. Avicularia none. Ooecia (?). 



Loc. Glenelg, Australia, incrusting stems of weed (own 

 collection). 



Both this species and the preceding belong to the section of 

 the genus of which M. catenularia, Jameson, is the best- 

 known representative. 



Membranipora corbula, n. sp. (PI. XVII. fig. 6.) 



Zooecia short-oval, distinct, front wall wholly membranous; 

 margins thin, bearing a number of somewhat compressed 

 spines (usually four on each side and one at the bottom), 

 which bend rather abruptly over the area, the extremities 

 meeting and crossing in the centre, but not uniting ; orifice 

 semicircular, on each side of it two tall and stout spines, of 

 which the foremost are usually curved and of gigantic size. 

 Ooecium shallow, rounded, smooth, much thrown back, with 

 a raised rib across the front, a little above the oral margin. 

 Avicularia none. 



Loc. Australia, on other Polyzoa (own collection). 



A very pretty form, with bright glittering cells, which 

 creeps over the stems of various Polyzoa. It has much the 

 appearance of a Membraniporella \ but the spines are never 

 united so as to form a single piece; it is properly ranked 

 amongst the spiniferous Membranipora. At the same time 

 it must be admitted that through such a form as the present 

 the two groups are brought very close together. 



An attempt will be made hereafter to give at least a rough 

 estimate of the number of described species (recent) which 

 are referable to the present genus. 



Family Microporidge. 



MiCROPOEA, Gray. 



1 Micropoia coriacea, Esper, var. (PL XVI. fig. 6.) 

 Zoozcia irregularly lozenge-shaped, front surface very slightly 

 convex, minutely granular, with numerous small punctures, 

 often covered with a brown epidermis ; margin thin, very 

 slightly granular or beaded, not much elevated, of about equal 

 size throughout (not enlarged at the base of the orifice) ; 

 orifice semicircular. Avicularia none. Ooecia large, rounded, 

 somewhat elongated, with a knob in front, from which two 



