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 Mantel! 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, f 



In this country three species only have, heretofore, I be 

 lieve, been observed, the granulata of Say, from the Tertiary 

 of Maryland the planicos ta of Lamarck, and the Blandingi, 

 found by Dr Blanding in the Tertiary of Camden, S. C. 



* Geo. Trans, vol. 3, second series. 



t See my observations on this species in the Introduction. 



