286 



DESCRIPTION OF A COLLECTION OF FOSSILS, 



this character on the middle or towards the base. Still, nearly all the specimens 

 being more or less imperfect, I am not certain that there is not also a difference 

 in outline. 



H. PONDEROSA, n. s., PI. 41, fig. 1. 



Shell large ; beaks prominent, placed about a third of the length from the 

 anterior end ; strongly incurved ; anterior end sloping nearly straight to the mid- 

 dle ; base broadly and pretty regularly rounded, not prominent; posterior end 

 most prominent near the base. Surface (of cast) marked by only very faint con- 

 centric lines, and with a broad faint depression towards the base a little posterior 



to the middle. 



Length, 4.5 inches ; width, from beak to base, 3.75 in. ; width of two valves, 



2.5 inches. 



Locality. From the elevated table land two leagues from Cajamarca. Con- 

 sidered Cretaceous by Dr. Raimondi. 



TELLINA, Linn. 

 ?T. Peruana, n. s., PI. 40, fig. 16. 



Shell lenticular, broad, sides very flattened; beaks minute, placed about a 

 third of the length from the anterior end; base and anterior end regularly rounded, 

 posterior end somewhat produced, sloping downwards from the beaks and rounded 

 sub-biangular. Surface marked by regular fine concentric striae. 



Figure. Natural size. 



Locality. From the coal mine of Pariatambo. 



Remarks. Not a rare species ; represented by a number of specimens. I have 

 referred it doubtfully to the above genus, because I have been unable to expose 

 the hinge, or even the pallial impression. 



CARDIUM, Linn. 

 Subgen. Peotocardia. 

 C. (P.) APPRESSUM, u. s., PL 40, fig. 11. 



Shell thin, not very convex, nearly equilateral, beaks central, anterior end most 

 prominent in the middle, posterior rounded, obliquely truncated; base broadly and 

 evenly rounded ; surface marked by small, regular concentric striee except on the 

 posterior side, which is covered with large radiating ribs, three or four of which, 

 running to the basal angle, are large and more prominent. 



Figure. Natural size. 



Localities. From the coal mine of Pariatambo, the Cerro of the Ventanillo, 



and near Ollon. 



