DESCRIPTION 
OF A 
NEW MOLLUSK 
FROM 
THE RED SANDSTONE, NEAR POTTSVILLE, PA. 
[Read before the Academy of Natural Sciences, May 2‘2d, 1855 ] 
UY 
ISAAC LEA. 
PHILADELPHIA. 
M ERR] HEW AND THOMPSON, PRINTERS, 
Meichant Street, above Fourth. 
1855. 'oceed. A.N.S. of Phil3" Vol. VH. 
Plate IV 
CYPRICARDIA LEIDYI. LEA. 
T Sinclair’s lith Phil3" 
MajjBB Id. {From the Proceedings of the Academy of Natural Sciences, May, 1865.] 
Description of a new Mollusk from the Red Sandstone near Pottsville, Pa. 
By Isaac Lea. 
A few weeks since Dr. Leidy had the kindness to place in my hands an in- 
teresting specimen, consisting of a cast of a bimusculose mollusk which that 
gentleman had found last summer at Tumbling Run dam, about a mile south- 
east of Pottsville. 
The discovery of this small specimen in these Red Sandstones (Formation No. 
11 of the Pennsylvania Survey, by Prof. Rogers) is of great importance, as it is 
believed to be the first mollusk which has been observed in these Red Sandstones, 
underlaying the conglomerate of the coal measures of Schuylkill County, known 
as the southern coal field of Pennsylvania, and consequently congenerie with 
the Sauropus primoevus, Lea, and Plumites, Rogers.* 
The extreme paucity of organic life yet observed in these Red Sandstones ex- 
cites the more interest, as the fact of such deficiency of types renders the position 
of this formation in the series a matter of doubt in the minds of some geologists. 
It is hoped that by patient research other mollusks may be discovered, and 
that, by the palaeontology of this portion of the Palaeozoic rocks, its true position 
may be determined. 
The specimen is simply a cast of the exterior of the two valves, entirely 
flattened out. In its facies it approaches the Cypricardia rhombea, Phill., (Geology 
of Yorkshire, pi. 5, f. 10,) from the Mountain Limestone of Northumberland 
* Mr. Hall, in the New York Reports, part 4, p. 292, describes a Cypricardiu 
{contracta) from the “ Conglomerate and Sandstone ” under the great western 
coal measures, near Panama, Chatauque County. It is quite oblong, and of much 
greater breadth and of a larger size than the species described herein. 4 
England. It is, however, rather more quadrate, and is a much smaller shell. It 
has strong affinities to Posidonia, particularly in the striae, and may possibly 
belong to that genus which seems to exist first in the Upper Silurian, and to rise 
to the superior portion of the Jurassic Formation. It also resembles the Microdon 
bellastriata, Con., (Hamilton Group,) described in the New York Reports, part 4, 
page 196, Geology, by James Hall. 
As the exterior form only is visible, the diagnosis must necessarily be very 
curt. It may be thus characterized until better specimens shall be obtained. 1 
name it after Dr. Leidy, who first discovered it. 
Cypricardia Leidyi. 
Shell oblong, round before and truncate behind, very inequilateral, striate ; 
dorsal and basal margin parallel; umbonial slope sharply carinate; anterior 
slope with an elevated line from the beak to the basal margin ; striae about 
twelve, very regular, and nearly equidistant. 
Length 2-20ths, breadth nearly 4-20ths of an inch. 
Observations.—This species is remarkable for its outline and striae. The dorsal 
and basal margins being parallel, and the posterior margin perpendicularly 
truncate, the angl<=90°. The strice cover the whole surface of the exterior, and 
are bent at an angle of 90° at the umbonial slope. The shell is accompanied 
on the specimen with some obscure impressed linear marks of a plant. 
(Plate I V. Tlie lower figure is magnified ten diameters.)