MEMBRANIPORA MINAX. 169 



folium the lamina is tumid, thin, and glistening ; the cells 

 are commonly rhomboidal or lozenge-shaped, but, as 

 I have mentioned, there are many variations, and there 

 seems to me to be less difference in this respect between 

 the two forms than Mr. Norman supposes. There is 

 usually no trace whatever of spines ; but on a small colony 

 from Wick, two are present at the top of the cell, placed 

 one at each side. 



There can, I think, be no doubt as to the identity of M. 

 sacculata, Norman, with the Crag species M. trifolium. In 

 the figures of the latter in Busk^s Monograph, the same 

 differences in the position of the avicularia are represented 

 as we find in the recent form (compare figs. 1 and 3 on 

 plate iii.). 



Membranipora MINAX, Busk. 



Plate XXII. figs. 2, 2 a, 2 6, 2 c. 



Membranipora minax {rhyncota in the description of the phite), Busk, 

 Zooph., Quart. Journ. Micr. Sc. viii. (1860), 125, ph xxv. 

 figs. \, 1 a,\b (not M. rhyncota, Crag Polyzoa). 



Membranipora Flemingii, forma minax, Smiif, CEfv. Kongl. Vet.-Akad. 

 Forhandl. 1867, no. 5, 367 and 409, pi. xx. fig. 43. 



Zooecia pyriform, narrowed below ; area occupying about 

 half the front of the cell, oval, inclosed by a much 

 raised, wall-like margin with a thin edge, two long 

 spines on each side near the top ; lamina smooth ; 

 aperture obscurely trifoliate, occupying about two 

 thirds of the area ; a large, raised, central avicular'mm 

 placed transversely on the margin at the bottom of the 

 area, or immediately below it, with a long and slen- 

 der mandible, tapering to a very fine point. Ooecia 

 small, subimmersed, globular, minutely granular. 



Primary cell 7a^«-like, with eleven or twelve, or some- 

 times with only five or six erect spines round the 

 margin of the circular or elliptical area [Smitt). 



