172 MOLLUSCA FROM THE CRAG. 



A small shell from the Paris basin, figured by M. Dcshayes, ' Coq. Foss. des Env. 

 de Paris,' tom. i, pi. vi, figs. 22 — 25, much resembles ours, and I applied to that 

 gentleman for permission to inspect one of his duj)licates, and he most obligingly sent 

 over to me, for comparison, the only two specimens he possesses, and for which I beg 

 to express my obligation. I fully concur with him in opinion that his fossil is speci- 

 fically distinct from the Crag shell: although it would have been desirable to have seen 

 a larger series of the Eocene shell, there is still so much difference between the two, 

 that unless a much greater amount of variation exists in the older Tertiary species 

 than is generally observable, they may very fairly be kept specifically distinct. The 

 Crag shell is much thicker, with a different arrangement of the dental furniture, and 

 there are no well-marked lateral teeth in the French shell ; and although the artist of 

 the figure above refeiTcd to has given an angular and pointed outhne to the base of 

 his shell, with a row of crenulations at the margin, I could not observe either of those 

 characters in the specimens submitted to my examination, nor are they so specially 

 mentioned in the text ; it is possible, however, they may be immature specimens, and 

 would consequently have the margins smooth.* 



AsTARTE,t J- Sowerby. IS 16. 



Venus (spec.) Linn. 



Peron.ea and Peroxeoderma (spec.) Voli. 



Tellina (spec.) VoU. 



Mactra (spec.) Monl. 



Cypkina (spec.) T%irt. 



Tridonta. Schum., 181/. 



Crassi.sa. Lam., 1818. 



Cypricaruia (sp.) Id. 



NiCANiA. Leach, 1819. 



GOODALUA. Turt., 1822. 



Mactroidea 



Mactrina. 



Okeada 



Brown, 1827. 



} 



Okeada. 1 



PvscHiA. J Itoullier, 18-16. 



* Since the above had gone to press Sir Charles Lyell has returned t'rom .America, whence he had 

 kindly undertaken to procure for me, if possible, a specimen of the Transatlantic species for examination, 

 and in a letter received by him from Mr. Conrad the following observation occurs, which I have the per- 

 mission of Sir Charles to publisli. 



" I have examined the shell sent by Jlr. Wood, and have compared it with the only specimen we have 

 of Enjcinellu ocalis. It is a smaller shell than the latter, of a more ovate form, and proportionally 

 narrower, still, I believe, they constitute one species. Our specimen has radiating lines, as seen'through a 

 magnifier, but this may be owing to a weathered surface. I have seen a recent shell from the Gulf of 

 Mexico, which I think is a congener with these fossils, but I have now none to refer to." 



t Etym., the Syrian name of Venus. 



