TO GEOLOGY. 71 
The figure is slightly enlarged. 
Observations. A beautiful little species, and likely to be 
taken for the young of the rotundata. It has, however, a 
less number of ribs, is more longitudinal, has a thicker shell, 
and has more elevated beaks—the hinge is remarkably 
thick. 
The genus Venericardia does not seem to exist in the 
older formations. Mr Mantell mentions one in the Chalk 
of Sussex, but has not determined the species. The V. 
Brogniarti is stated to be from the Sandstone.* Six are 
mentioned by Mr Sowerby as existing in the London Clay, 
and four are by him ascribed to the Crag. The well 
known V. planicosta exists in the London and Paris basins. 
M. Deshayes, uniting the Venericardia and Cardita, gives 
fifty for the Tertiary of Europe. Mr Conrad gives for 
American localities of this species, Maryland and Ala- 
bama.t 
In this country three species only have, heretofore, I be- 
lieve, been observed, the granulata of Say, from the Tertiary 
of Maryland—the planicosta of Lamarck, and the Blandingi, 
found by Dr Blanding in the Tertiary of Camden, 8. C. 
* Geo. Trans. vol. 3, second series. 
+ See my observations on this species in the Introduction. 
