220 PROCEEDINGS OF THE ACADEMY OP [1819. 



Ostrea divaricata, Lea. " Contributions to Geology," p. 90, pi. 3, fig. 69. 

 0. selUvformis, Conrad, pars ? 



This oyster is referred without doubt both by Nyst (" Coquil- 

 les et Polypiers Fossiles," 1843, p. 323) and Giebel {Repertorium 

 to Goldfuss' u Petrefacta Germanise," 1866, p. 41) to the O.flabel- 

 lula of Lamarck, which is a very variable, and one of the most 

 widely diffused forms of fossil oyster. It is cited by D'Orbigny 

 (Prodr. de paleon.) as occurring at Claiborne, Ala., and by Des- 

 hayes (Animaux s. vert., bassin de Paris) also at Cutch in India 

 and Cairo in Egypt. 



Pecten Deshayesii, Lea. Contr. p. 87, pi. 3, fig. 66 

 (et P. Lyelli, ace. to Conrad l). 



This Pecten is referred with but little doubt by Nyst (Coqu. et 

 PoL, p. 288) to P.opercularis, Lamk., which species, however, be- 

 longs to a much more recent period than the Eocene of Alabama. 

 On the assurance of identity Nyst in 1836 founded upon a new 

 Belgian Pecten the specific name of Deshayesii, but his fossil must 

 be carefully distinguished from the American one in question. 

 Having seen but one example of Lea's species I am unable to 

 make the proper comparisons. 



Cardita rotunda, Lea. Contr. p. 70, pi. 2, fig. 48, as Venericardia. 



This species very closely resembles the Cardita imbricata of 

 Lamarck, to which, in the absence of specimens, it is with some 

 hesitation referred by Nyst (p. 209), and also by Bronn {Index 

 Palseontologicus, I. 226). The only difference that I could detect 

 between the two species, on an examination of numerous speci- 

 mens from Grignon, France, and Claiborne, Ala., was that in the 

 C. imbricata there was a tendency in the ribs of the posterior slope 

 to become crowded. As some specimens of both forms, however, 

 could not readily be distinguished from each other, I believe this 

 circumstance to be mainly accidental, and therefore consider the 

 G. rotunda as certainly nothing more than a mere variety of G. 

 imbricata. 



Cardita planicosta, Lamk. 



This species of Cardita, which is so extensively distributed over 

 the Eocene deposits of Europe, is certainly identical with the simi- 

 lar forms of Cardita found in the same formation of the United 

 States. Lea (Cont. p. 19) states that according to his observa- 

 tions the American species differs from the European in the num- 



