LAMELLIBRANCHIA TA . 
485 
Cypricardinia indenta. 
PLATE LXX&, PIGS. G-1G, 23; and PLATE XCVI, FIG. 2. 
Cypi'icardites indenta, Conrad. Jour. Acad. Nat. Sci., Phila., vol. viii, p. 244, pi. 12, fig. 12. 1842. 
In part Cypricardinia indenta (Conrad), Hall. Prelim. Notice Lamellibranchiata, 2, p. 83. 1870. 
“ “ “ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: 
PI. 79, figs. 6-23. 1883. 
Cypricardites inflata, Conrad. Jour. Acad. Nat. Sci., Phila., vol. viii, p. 246, pi. 15, fig. 2. 1S42. 
Shell of medium size, sub-rhomboid-ovate ; length more than one-third greater 
than the height; basal margin nearly straight, slightly sinuate anterior to 
the middle. Posterior extremity abruptly rounded below and obliquely 
truncate above. Cardinal line straight, oblique. Anterior end very short, 
rounded below. 
Right valve very convex, often extremely gibbous. Left valve usually 
depressed-convex below and posteriorly, becoming moderately gibbous in the 
umbonal region. 
Beaks nearly anterior, small and appressed, rising but little above the 
hinge-line. Cincture distinct on the right valve, less marked upon the left 
valve. Umbonal slope rounded and prominent on the right valve, sub- 
angular on the left valve. 
Surface marked by extremely fine concentric stride and by unequally distant 
but somewhat regular, lamellose, imbricating, concentric undulations ; and in 
well-preserved specimens the entire surface is marked by fine striae, which radi¬ 
ate from the apex of the shell, and in some conditions of preservation the sur¬ 
face shows a second set of striae vertical to the direction of the lamellae. 
Four specimens measure respectively 11, 14, 18 and 20 mm. in length, 
and 7, 8, 11 and 11 mm. in height. 
This species is smaller than the preceding, the right valve, when well- 
preserved, is more gibbous, the depression or sinus above the umbonal slope is 
not so distinctly defined, and the posterior margin is not sinuate. This spe¬ 
cies probably includes the form described as Cypricardites injlata by Mr. Conrad, 
which represents a gibbous specimen as preserved in the limestone. The speci¬ 
mens, figs. 6, 7, 8, are from near the original locality of that species. 
Formations and localities. In the Corniferous limestone, at Babcock’s hill, 
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