320 [APRIL, 
Notes on Shells. 
By T. A. Conran. 
Dreissena, Van Beneden. 
There is but one species of this genus known to inhabit the waters of North 
America. It is a small shell, very abundant in Virginia, attached by its 
byssus to the Ostrea virginiana. I described it in the Journal of the Academy 
of Natural Sciences, vol. vi. p. 263, pl. 11, fig. 13, under the name of Mytilus 
leucopheatus. 
Artemis, Poli. 
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. concentrica.) 
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, pl. 16, fig. 1. 
Gualt. t. 76, fig. F. 
Favanne, t. 48, fig. 3. 
Venus concentrica, Born. t. 5, fig. 5. 
TInhabits the coast of Florida. 
2. A. ELEGANS, Coz., Miocene Shells, p. 67, pl. 38, fig. 1. 
Encyc. Method. t. 279, fig. 2. 
Lister, t. 288. 
Chemn. vii. pl. 37, fig. 392. 
A. concentrica, Reeve, (not Born) Conch. Icon. pl. 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. piscus, Reeve, Conch. Icon. pl. 11, fig. 9. 
Cytherea concentrica, Chenu, (not Born,) pl. 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 Spectes. 
A. LENTICULARIS. 
Cytherea lenticularis, Rodgers, Trans. Amer. Philos. Soc., 2d series, vi., p. 
372, pl. 28, fig. 1. 
_ Locality. Eastern Virginia, in the Eocene. 
A. EXCAVATA. 
Cytherea excavata, Morton, Cretaceous Group of the United States, p. 67, 
pl. 5, fig. 1. 
Locality. Arneytown, N. J., in cretaceous green sand. 
ACANTHINA, Fischer. 
Monoceros, Lam. 
This genus, very nearly connected with Purpura, 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 Deshayes in his Coq. Foss. 
Viz. obtusum, semicostatum and patulum, must either be arranged in the present 
genus or in Sowerby’s genus Gastridium, 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 Gastripium, Sowerby. 
A. vetusta, Con. 
Monoceros vetustus, Con., Foss. Shells, p. 37, pl. 15, fig. 3. 
M. pyruloides, Lea, Contributions, p. 161, pl. 5, fig. 166. 
M. fusiformis, ibe ib. p- 162, pl. 5, fig. 167. 
