1881] MR. E. A. SMITH ON THE GENUS GOULDIA. 491 



modesta are small forms of the genus Crassatella. Gouldim minima, 

 ceriiia, australis, and perhaps dilecta, which I only know from 

 description, prove to helong to Circe ; and G. lamellosa is unknown 

 to me. Of the former group, four species, viz. guadeloupensis, 

 parva, mactracea, and pfelfferi, are, I believe, one and the same 

 shell, and may retain d'Orbigny's name, which was the first pub- 

 lished. In conclusion I will add the description of a small species 

 of Crassatella from the west coast of Africa. 



Crassatella knockeri, sp. nov. 



Shell small, transparent whitish, angular at the beaks, rounded 

 on the ventral margins, compressed, a little inequilateral, concentri- 

 cally ribbed. Ribs strong, terminating anteriorly at the narrow 

 shallow lunule, and posteriorly defining a very narrow linear dorsal 

 area separated by deep sulci rather broader than the ridges. Um- 

 bones small, smooth, hyaline, approximated ; anterior and hinder 

 dorsal slopes subequal, the former feebly concave, the latter recti- 

 linear. Hinge consisting of two cardinal teeth in the right valve, 

 the anterior one very conspicuous, the other very small ; and two in 

 the left of more equal size. Lateral teeth elongate, one on the pos- 

 terior slope of the right valve, fitting into a corresponding groove in 

 the left, and one on the anterior slope of the latter received by a 

 groove in the right. Ligament placed in a cavity immediately pos- 

 terior to the two cardinal teeth of the left valve, and between those 

 of the right. Interior of valves glossy, exhibiting the external rib- 

 bing, owing to their transparency, prettily crenulated within along the 

 ventral margin. Length from umbo to opposite margin 4^ millim., 

 width 41, diam. 1^. 



Hab. Whydah, West Africa (dredged by Captain Knocker, R.N.). 



Although of small size, this pretty shell appears to be adult ; and 

 the crenulated inner edge of the valves indicates maturity. Its 

 transparent texture is peculiar ; and it is very stoutly costate for so 

 small a species. 



May 3, 1881. 

 Professor Flower, LL.D,, F.R.S., President, in the Chair. 



The following papers were read : — 



2,2* 



