320 [April, 



Notes on Shells* 



By T. A. Conrad. 



DreissenAj Van Beneden. 



There Is but one species of this genus known to inhabit the waters of North 

 America. It is a small shtll, very abundant in Virginia, attached by its 

 byssus to the Ostrea virglniana. I described it in the Journal of the Academy 

 of Natural Sciences, vol. vi. p. 263, pi. 11, fig. 13, under the name of Mytilus 

 leiicophceatiis, 



Artemis, Pali. 



There are three species of this genus on the Atlantic coast of the United 

 States, one of which occurs fossil in the Miocene of Virginia, {A. co7icentrica.) 

 As they do not appear to be correctly named in Reeve's monograph, the follow- 

 ing corrections are submitted : 



1. A. CONCENTRICA. 



A. acetabulum^ Con., Miocene Shells, p. 29, pi. 16, fig. 1. 

 Gualt. t. 76, fig. F. 

 Favanne, t. 48, fig. 3. 

 Venus concentrica. Born. t. 5, fig. 5. 

 Inhabits the coast of Florida. 



2. A. ELEGANs,'Co?i., Miocenc Shells, p. 67, pi. 38, fig. 1. 

 Encyc. Method, t. 279, fig. 2. 



Lister, t. 288. 

 Chemn. vii. pi. 37, fig. 392. 



A. concentrica^ Reeve, (not Born) Conch. Icon. pi. 11, fig. 8. 

 Inhabits the southern coast of Florida. Common in Tampa Bay. Fossil in 

 Post-Pliocene on the Neuse river, North Carolina. 



3. A. DISCUS, Reeve, Conch. Icon. pi. 11, fig. 9. 

 Cytherea concentrica, Chenu, (not Born,) pi. 10, fig. 5. 



Inhabits the coasts of the Middle and Southern States. It has been found as 

 far north as Cape May, and is common in Tampa Bay, Florida. 



Fossil Species. 



A. LENTICULARIS. 



Cytherea lenticvlaris^ Rodgers, Trans. Amer. Philos. Soc, 2d series, vi., p. 

 372, pi. 28, fig. 1. 



Locality. Eastern Virginia, in the Eocene. 



A. EXCAVATA. 



Cytherea excavata, Morton, Cretaceous Group of the United States, p. 67, 

 pi. 5, fig. 1. 



Locality. Arneytown, N. J., in cretaceous green sand. 



ACANTHINA, Fischer. 



' MoNOCERos, Lam. 



This genus, very nearly connected with Fnrpnrai does not abound in species 

 either recent or fossil. It makes its first appearance in the Eocene, and I have 

 not met with it anywhere in this country, except in the older Eocene of Ala- 

 bama. Three species referred to Buccinum by Deshiiyes in his Coq. Foss. 

 viz. ohtnsum, semicostatum and jjatnlum, must either be arranged in the present 

 genus or in Sowerby's genus Gastrid/icm, which does not materially differ from 

 Acanthina, the only variation consisting in its small or obsolete tooth. In the 

 Claiborne species the tooth, though small, is never obsolete in perfect spe- 

 cimens. 



Sub-Genus Gastridium, Sowerhy. 



A. vetusta. Con. 

 Monoceros vetustus, Con., Foss. Shells, p. 37, pi. 15, fig. 3. 

 M. 2)yrnloidcs, Lea, Contributions, p. 161, pi. 5, fig. 166. 

 M.fHsiformis, ib. ib. p. 162, pi. 5, fig. 167. 



