SHUMARD—CRETACEOUS FOSSILS. 601 
rior impression subcircular, or subquadrate; sinus rather 
broad, triangular, scarcely reaching the middle of the shell. 
ce ornamented with remarkably fine, concentric strie of 
owth. 
Dimensions of an average specimen, length, 0.97 of an 
inch; width, 0.74; thickness, 0.45. 
This shell may be compared with C. Owenana of Meek and 
Hayden, (Proc. Acad. Nat. Sci., Philadelphia, Vol. —, p. —) 
with which it agrees in several respects, and it probably oc- 
cupies a similar geological position. The differences seem to 
consist mainly in the absence of concentric wrinkles on the 
a shorter pallial sinus, and smaller size, of the Texan 
she 
Locality.—In Septaria of the marly clay at the base of the 
ower Cretaceous Strata, Red River, Lamar County. Col- 
lected by Dr. G. G. Shumard. ee 
GENUS TAPES. 
T. Hrrearpi, n. sp. 
tow lanceolate ; pallial sinus lingueform extending above the 
middle of the height of the shell. The surface —— are 
Length, 2 inches; width, 1.27; thickness, 0.66. 
_ Locality Bluffs of Red River, Lamar and Fannin Coun- 
Hes, occurring in Septaria of the marly clay, near the base of 
the Lower Cretaceous. i 
Named in honor of Dr. E. W. Hilgard, State Geologist A 
Mississippi. Collected by Dr. G. G. Shumard. 
GENUS ARCA. 
A, Prourrana, 2. sp. 
hell Somewhat trapezoidal, very gibbous, a little wider 
oe long; buceal and pallial margins rounded; and margin 
obliquely truncate ; umbonial region very gibbous ; angula- 
-. Posteriorly ; posterior slope declining rapidly to the mar- 
a 4 sharp elevated carina or fold extending in a curve ar 
* Posterior side of the beak to near the middle of the an: 
* 
Sia ARTS a ye cL gg 
