TO GEOLOGY. 55 



Observations. Differs from the ovalis, which it most resem 

 bles, in being smooth, more compressed and more angular. 



E. nana. Plate 1. Fig. 26. 



Description. Shell rotundo-oblique, compressed, angu 

 lar above, subequilateral, concentrically striate ; substance 

 of the shell rather thin ; beaks pointed ; cicatrices imper 

 ceptible ; cavity of the shell shallow of the beak angu 

 lar ; margin entire. 



Diara. .1, Length 5-20ths, Breadth 5-20ths, of an inch. 



Observations. Closely resembles the rotunda. It has, 

 however, somewhat larger concentric striae is a much 

 smaller shell, and is more oblique. 



GENUS LUCINA. Lamarck. 



L. compressa. Plate 1. Fig. 27. 



Description. Shell subrotund, much compressed, very 

 finely and concentrically striate, equilateral ; beaks small 

 and pointed ; lunule small and cordate ; anterior cicatrix 

 deeply impressed, extending nearly to the basal margin ; 

 palleal impression irregular ; cavity of the shell shallow 

 and rough, having an impressed furrow across its centre ; 

 margin entire. 



Diam. .6, Length 1.5, Breadth 1.7, of an inch. 



Observations. This species is very fragile, scarcely bear- 



