TO GEOLOGY. 53 
science of geology, and very few have laboured more suc- 
cessfully to add new facts to establish its philosophy. 
; 
E. subtrigonia. Plate 1. Fig. 22. 
Description. Shell subtriangular, somewhat inflated, 
inequilateral, polished, obtusely angular before and at top; 
substance of the shell thin; anterior slope furnished with 
asmall fold; beaks slightly elevated, pointed ; cicatrices 
perceptible ; cavity of the shell rather shallow ; inferior 
portion of the margin minutely crenulate. 
Diam. .2, Length .3, Breadth .5, of an inch. 
Observations. There is a very close resemblance be- 
tween this and the Bucklandii, and had there not been so 
much disparity in the size of the shell and thickness of the 
valve, I should not have been disposed to separate them. 
The valves of three specimens are before me. They are 
of the same size, and have every appearance of being adult. 
E. veneriformis. Plate 1. Fig. 23. 
Description. Shell ovately triangular, transverse, rather 
compressed, inequilateral, polished ; substance of the shell 
thin ; beaks pointed ; cicatrices perceptible ; cavity of the 
beaks shallow; inferior portion of the margin very mi- 
nutely crenulate. 
Diam. 3-20ths, Length .2, Breadth .3, of an inch. 
Observations. This small species has a close resem- 
blance to the last described. It differs chiefly in size and 
