1853.] 199 
many littoral genera as Plezrotoma, the species of which are very abundant in 
specimens, Turritella, Natica, Terebra, Oliva, and various others, indicate shallow 
water, and the abundance of comminuted shells and waterworn specimens attest 
the vicinity of a sea beach. 
The well known Miocene deposits are remarkably unlike that of Vicksburg, 
in the abundance of large species of Venus, Fulgur, Perna and Panopea, some of 
which genera, with their peculiar species in every latitude, render the Miocene 
period recognizable at a glance. Indeed it is singular that the distinctive cha- 
racter of this formation should be so strongly marked over an extent of 400 
miles north and south. Even the Venus alveata,a common Maryland fossil, 
seems to be abundant beneath the level of the sea, on Sullivan’s Island, near 
Charleston, and another Maryland fossil, which I have named Ecphora 4-costata, 
(Fusus 4-costatus of Say,) was found on the beach of St. Simon’s Island, Georgia. 
Both localities are south of the latitude of Vicksburg, the Georgia one nearly a 
degree farther south. ‘The researches of Mr. ‘Tuomey, in South Carolina, have 
brought to light at least 26 species, which are known to occur as far north as 
St. Mary’s river, Maryland. From this comparison of groups it seems obvious 
that the Vicksburg deposit must be of earlier origin than the fossiliferous Ter- 
tiary strata of Maryland, Virginia, North and South Carolina, which seem all 
to be of one geological era, though Mr. Tuomey refers those of South Carolina 
to the Older Pliocene period, Whether the Mississippi formation should be 
termed an Older Miocene or a Newer Eocene, may yet be doubtful, but that it 
is intermediate between the Lower and Middle Tertiary, and differing widely 
from either in the period of its deposition, is obvious. 
A careful exploration of the St. Domingo locality will probably clear up all 
doubts on the subject. 
In conclusion, I may observe, that besides the Turbinella Wilsont and Oniseia 
harpula, the Cassidaria levigata Forbes is identical with my C. lintea, thue 
giving three species common to the Vicksburg and St. Domingo groups. 
Notes on Shells, with Descriptions of new Spectes. 
By T. A. Conran. 
Crypropon, Con. 
The name of this genus, founded on Mya cancellata, having been previously 
applied by Turton to another group of bivalves, and now adopted by some 
conchologists, it is necessary to change it, and I therefore propose 
SCHIZOTHERUS, 
in allusion to the profound channel which indents the hinge on both sides of the 
cardinal teeth. 
Scuizotu#rus Nutrratiu. 
Cryptodon Nuttalliz, Con., Journ. A. N.S. vol. 7, p- 225, pl. 18, fig. 1. 
Unto. | 
Unto Morront, Con., Dec. 1835. — “~ 
U. turgidus, Lea, 1837. a me 
Mr. Lea’s description of this species was read at a meeting of the Philo 
sophical Society in Dec. 1834, but 20¢ published before 1837. ~ 
Miocene species ? 
OstTREA. 
Ostrea Titan. Elliptical or oblong ; extremely thick and ponderous, contracted 
towards the hinge; ligament cavity profound; upper valve slightly arched ; 
surface coarsely Jaminated. WLength 10¢ inches. 
