TO GEOLOGY. 55 
Observations. Differs from the ovals, which it most resem- 
bles, in being smooth, more compressed and more angular. 
E. nana. Plate l. 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. 
Diam. .1, Length 5-20ths, Breadth 5-20ths, of an inch. 
Observations. Closely resembles the rotunda. It has, 
however, somewhat larger concentric strie—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- 
