TO GEOLOGY. 63 
A. parva. Plate 2. Fig. 37. 
Description. Shell triangular, rounded below, acutely 
angular above, compressed, equilateral, concentrically and 
closely striate; beaks elevated, pointed; lunule large, 
lanceolate ; cardinal teeth small, the posterior margin fur- 
nished with a long straight lateral one ; cicatrices scarcely 
visible ; margin crenulate. 
Diam. =...) - Length .1, Breadth .1, of an inch. 
The smaller figure is of the size of nature. 
Observations. Although this and the two following spe- 
cies do not accord entirely with Sowerby’s generic descrip- 
tion of Astarte, nor that of Lamarck under the name of 
Crassina, inasmuch as these have a long, straight, lateral 
tooth ; I have preferred placing them there, as they agree 
in all the other generic characters, thinking it unnecessary 
to make a new genus for them. 
The species above described is more elevated and more 
acutely angular at the beaks than the others. Its strize 
are much finer, and it is supposed to be emarginate imme- 
diately under the point of the beaks. 
4 
4. mmor. Plate 2. Fig. 38. 
Description. Shell triangular, rounded below, angular 
above, compressed, equilateral, concentrically and widely 
striate ; beaks elevated, pointed ; lunuie large, lanceolate ; 
cardinal teeth small, the posterior margin furnished with 
