188 AMERICAN JOURNAL 



NOTES ON FOSSIL SHELLS AND DESCRIPTIONS OF NEW 



SPECIES. 



BY T. A. CONRAD. 



SOLENID^. 



LEPTOSOLEN, Conrad. 



This genus is very nearly allied to Solena, Browne, but, hav- 

 ing obtained a more complete view of the interior since the 

 generic character was published, I find that the anterior mus- 

 cular impression is chiefly anterior to, though its posterior end 

 nearly covers, the rib, which is prominent in the umbonal 

 region, truncated behind, sloping anteriorly, and situated behind 

 the line of the apex. The upper margin of the muscular im- 

 pression is on a line with the interior hinge line. In Solena the 

 tooth is narrowest on the hinge plate, and there is a small 

 pit before it ; but in Leptosolen the tooth is broadest on the 

 hinge plate, and tapers to a very acute edge, which is expanded 

 in the direction of the shell's diameter. 



ANATINID^. 



PERIPLOMA, Schum. 



The Anatina alta, C. B. Adams, proving to be a Periploma, 

 it is necessary to substitute another name for P. alta, Conrad, 

 figured in Am. Journ. Conch., vol. ii., pi. 4, fig. 10. I propose 

 the name P. peralta, Conrad. 



MACTRA, Lin. 

 M. ViRGiNiANA, Conrad. 



Description. — Triangular, elongated, hatchet-shaped, equi- 

 lateral, compressed ; anterior subcuneate, obliquely truncated at 



