OF DENISON UNIVERSITY. 
41 
Genus Oracardia. Gen. n. 
Dexiobia, WiNCHELL (pars. ?) {Eiy. oraios-kardia.) Type A. ornata. 
Shell somewhat inequilateral, more or less inequivalve, both 
valves quite ventrcose, with a strongly curved, acute, elevated beak, 
which inclines forward at the apex. Hinge-line extended, produced 
posteriorly, furnished with a thickened ridge or cartilage plate. The 
beaks are separated from the hinge by a pseudo-area which is elevated 
and more or less arched under the beak. 
Surface marked by radiating lines which do not tend to increase 
in number toward the front. 
ORACARDIA ORNATA, sp. n. 
(Plate IV, Fig. 8, 9, 10.) 
Cf. Dexiobia halli^ Win. 
With the characters of the genus. Shell transversely semi-ellipti- 
cal, somewhat oblique, hinge-line as long as the shell, straight ; beak 
acute, oblique, recurved, elevated ; anterior slope concave, flattened, 
producing a double ridge, posterior slope more regular, convex or 
flattened ; greatest convexity at about one-third the height from the 
beak, front portions curving very abrubtly to the broadly curved low- 
er margins ; anterior margin meeting the hinge by a gentle curve. 
Surface marked by rounded distinct ribs which are closely set and con- 
tinue for the most part from beak to lower margin, also by irregular 
concentric folds. 
The area is acute below the beak. Judging from our specimens 
the right valve is somewhat more convex than the left but not remark- 
ably so. Height of a left valve, 22 mm., length, 27 mm., convexity 
9 mm., six striae occupy a distance of 5 mm., at the lower margin. 
Several specimens were found near the top of the freestone of middle 
Waverly. A very small specimen apparently of this species was ob- 
tained 108 feet above conglomerate I in Richland Co. Dexiobia halli, 
and Cardiomorpha rhomboidea may both refer to this species, though 
the description of the latter is insufflcient and the former is said to be 
smooth. 
