﻿NEW ORETACEOUS AND EOCENE FOSSILS. 291 



thin, much impressed; lower valve flat or slightly concave; both valves radiated 

 with raised lines, which are ornamented with small foliated spines. 

 Locality. — Tennessee. Mr. Safford. 



Placunanomia lineata. PI. 46, fig. 20. Subovate, thin, much compressed, irregu- 

 lar; lower valve concave, obsoletely radiate ; near the summit is a resemblance to a 

 triangular plate inserted in the shell with a raised margin ; this portion is longitu- 

 dinally minutely striate and resembles one of the opercular valves of a Balanus ; 

 upper valve convex, lobed or twisted ; radiated with about thirty rugose, slightly 

 raised, subaculeated lines ; surface rugose. 



Locality. — Tennessee. Mr. Safford. 



The hinge of these shells differs from that of the recent Placunanomia in the 

 upper valve being destitute of the diverging teeth. In both species the orifice is com- 

 pletely closed by the plug ov ossified tendon of adhesion. 



EGHINODE RMS. 

 CASSIDULUS, Lam. 



Cassidulus abruptus. Obtusely ovate, flat beneath, very convex above ; lateral 

 margins convex, anterior slope more oblique ; posterior .slope abrupt, ambulacra 

 lanceolate; mouth central; anus small, oblong oval, with a furrow beneath. 



Locality. — Tippah Co., Miss. Dr. Spillman. 



Cassidulus subquadratus. PL 47, fig. 19. Suborbicular, flat beneath, flexuous 

 posteriorly ; lateral and end slopes truncated ; anus very large, obtusely ovate, with a 

 depression beneath extending to the margin which at that point is salient ; ambulacra 

 lanceolate. 



Length 3i inches. Diameter 21 inches. Heighth If inches. 



Locality, — Occurs with the preceding. Dr. Spillman. 



Dr. Showalter, of Uniontown, Alabama, has sent me some Eocene shells which 

 appear to be new, and are from a locality further north in Alabama than any Mr. 

 Tuomey had explored. With these I have included a description of an Eocene shell 

 from Mississippi sent by Dr. Spillman, and a few species from Alabama in the collec- 

 tion of the Academy. 



EX ILIA, Conrad, 



Exilia pergraoilis. PL 4^, fig. 34. Narrow-fusiform; volutions twelve, convex, 



with slightly curved, numerous, narrow ribs, and fine closely-arranged revolving 



74 



