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 

 a small 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 



