412 PALEONTOLOGY OF NEW YORK. 



slope angular, continuing to the post-inferior margin. Post-cardinal slope 

 concave. 



Test thick, body of the shell marked by numerous radii, between which 

 are undulating lamellose concentric stride. When the shell is exfoliated the 

 nulii liecome stronger and the intermediate surfjice is marked by fine radiiit- 

 ing strisB. With the growth of the shell the anterior rays become greatly 

 strengthened and semi-tubular. 



The cast of the foot-sheath is bilobed, and doubly pointed behind. 



Two specimens measure respectively 50 and 60 mm. in length, 25 and 32 

 mm. in height, and 26 and 30 mm. in the depth of both valves. 



This species bears a close resemblance to the elongate forms of C. cuneus. 

 There is, however, no tendency to a duplication of the ribs, which is a common 

 feature in the specimens from the Schoharie grit. 



Formatum and locality. In the shales of the Hamilton group, near Cumber- 

 land, Md. 



CONOCARDIUM EbOBACEOM. 



PLATE LXVIII, FIGS. 20-23. 



Cunocardium Eboraceum, Hall. Thirteenth Rep. N. Y. State Cab. Nat. Hist., p. 91. I860. 



" " " Pal. N. Y., vol. V, pt. 1. Plates and Explanations : PI. «8, figs. 20-23. 



1883. 



Shell small, sub-ovate ; length less than twice the height ; basal margin gently 

 curving. Posterior end obliquely truncate. Anterior end abruptly con- 

 tracted, nasute, gaping. 



Valves ventricose in the middle. 



Beaks a little anterior to the middle, incurved. Umbonal slope angular, 

 and just within the cardinal slope the shell is marked by five or six angular 

 radiating ribs. The central portion of the post-cardinal slope is unknown. 



Test thick. Body and anterior portion of the shell marked by obscure 

 plications and by strong, concentric, reflexed lamellose striae. The radii are 

 continued beyond the concentric laminae at the margin, as strong interlock- 

 ing denticulations. 



In well-preserved specimens the concentric laminae from the umbonal 



