TO GEOLOGY. 45 
true JMactre. From the description and figures, I should 
not hesitate to abstract them from that genus. M. De- 
shayes gives fourteen species in his Tertiary Tables, six 
are from the Miocene of Bourdeaux and Dax. In this coun- 
try, Mr Say seems first to have observed it in the Tertiary 
of Maryland.* More recently Mr Conrad has discovered 
in the same formation two new species, JV. ponderosa, at 
St Mary’s river, Maryland, and MM. delumbis, at St James’s 
river, near Smithfield, Virginia. ; 
FAMILY CORBULEA. 
GENUS CORBULA. Brugiere. 
C. Alubamiensis. Plate 1. Fig. 12. 
Description. Shell inflated, triangular-ovate, angular 
behind, transversely and finely striate, inequilateral, very 
inequivalve, anterior part the larger; beaks incurved and 
rather pointed ; tooth of the right valve large, pointed and 
fitting under the beak of the left valve; posterior basal 
margin straight or slightly emarginated ; the two great 
cicatrices distinctly impressed ; cavity of the valves deep. 
Diam. 7-20ths, Length .4, Breadth .7, of an inch. 
Observations. This is the largest species I have seen 
from our formations. It has a strong resemblance to C. 
* Journal of the Academy of Natural Sciences of Philadelphia, vol. 4, 
p. 152, 
