FROM THE TERTIARY OF VIRGINIA. 269 
and carina at right angles. The carina is placed immediately below the middle of the 
whorls, and, in some specimens, between it and the lower suture is another smaller one. 
When this latter is not present, it is replaced by a stria. Between the carina and upper 
suture there are generally two strie, which vary in size. ‘hose on the base are much 
smaller than those on the whorls. ‘The sutures are small and triangular. 
This shell is unusually short and thick for a Cerithium, and its effuse mouth has 
hardly the character of the canal of that genus. 
C. DEDALEUM, Pu. 37. Fie. 91. 
C. testd subulatd, tenui, imperforatd, costatd, striatd; spird attenuatd, sub-ovatd, mamillatd, ad apicem levi et 
politd; suturis linearibus, parvis; anfractibus septem, planulatis; costis longitudinalibus, crebris, levibus, planulatis; 
striis transversis, crebris, profundis; ultimo anfractu rotundato; basi striata, politda; aperturd arctatd, sub-quadratd, 
superne angulatd, inferne effusd; labro acuto. 
Shell subulate, thin, imperforate, costate, striate; spire attenuate, sub-ovate, mamillate, smooth and polished near 
the apex; sutures small, linear; whorls seven, flattened; stria transverse, numerous, deep; cost# longitudinal, nume- 
rous, smooth, flattened ; last whorl rounded; base striate, polished, mouth narrow, sub-quadrate; angulate above, effuse 
below; outer lip acute. 
Length .15. Breadth .05 of an inch. 
Remarks.—TVhe sculpture of this shell is not unlike that of the Pasithea subula, herein 
described. 
With this shell, as with the preceding, I feel in some doubt as to the genus to which 
it properly belongs. 
C. MONILIFERUM, PL. 87. Fic. 92. 
C. testi subulatd, sinistrali, crassa, imperforatd, costatd; spird attenuatd, conicd; suturis minimis; anfractibus 
decem, planis; costis tribus, transversis, noduliferis, duabus extremis magnis, und medio parviore; anfractu ultimo 
rotundato; basi costis tribus, levibus, transversis; aperturd elongato-quadratd; columelld levi, politd; canale profundo, 
brevi. 
Shell subulate, sinistral, thick, imperforate, costate; spire attenuate, conical; sutures very small; whorls ten, flat; 
coste three, transverse, noduliferous, two extreme ones large, the middle one smaller; last whorl rounded; base with 
three transverse, smooth ribs; mouth elongately quadrate; columella smooth, polished; canal deep, short. 
Length .22. Breadth .09 of an inch. 
Remarks.—The middle costa is smaller than the two outer ones; it gradually decreases 
on the upper whorls, and finally becomes obsolete near the apex. ‘The sutures are very 
small, and the whorls perfectly flat, so that it is difficult to determine their number. 
This shell approaches the C. nigrocinctum, Adams, a recent species from our coast, 
but may be distinguished by its greater proportionate length, flatness of the whorls, and 
the difference between the size of the ribs, It is also allied to the C. perversum, another 
recent shell, but it is much smaller, and the ribs are strictly noduliferous, while in the 
C. perversum, they intersect longitudinal sulci. The three smooth basal coste consti- 
tute another character peculiar, I believe, to this shell. 
GENUS PLEUROTOMA. 
P. Lunatum, Pu. 37. Fic. 93. 
P. testd elongato-fusiformi, crassd, glabrd, nitente, imperforatd, costatd; spird attenuata, mamillatd, ad apicem 
levi; suturis flexuosis, minimis; anfractibus decem, medio angulatis, inferné convewis et costatis, superne concavis et 
VOL. IX.—7]1 
