36 NEW YORK STATE MUSEUM 



transverse; the byssal groove is profound from the umbo down, and 

 the auricle sharply convex. 



The entire surface is covered with fine, elevated radial striae of 

 subequal size and separated by grooves of the same width. Over the 

 auricle and adjoining surface the striae are coarser and are crossed by 

 strongly cancellating concentric lines, which produce projecting processes 

 on the radii, in places taking the form of small spinules. Low varices 

 of growth occur at irregular intervals. 



Cypricardinia indenta Conrad 



Plate 4, flg. 18-20 



1892. Cypricardinia cf. lamellosa Clarke, op. cit. p. 413 



For figures of C. lamellosa see Paleontology of New York. v. 3, 

 pi. 49a, fig. 50 a-c; of C. planulata and C. indenta, op. cit. v. 5, pt 1, 

 pi. 79, fig. 1-23 



The specific type of Cypricardinia lamellosa Hall, described 

 from small specimens from the shaly (New Scotland) limestone, is con- 

 tinued upward into the Onondaga and Hamilton faunas. The figured 

 examples of the C. planulata of the Schoharie grit show a shell 

 of very large size, possessing the characteristic lamellate surface, but 

 associated with it is a small shell of rather different outline, which it 

 will be difficult to separate from C. lamellosa. Cypricardinia 

 indenta occurs both in the Onondaga limestone and Hamilton shales. 

 Internal casts of these shells, the usual condition in which they are 

 found, show some slight difference in the character of the broad, con- 

 centric ridges of the surface; but, when the exterior is retained, it 

 appears to be in all cases without material variation in the form, 

 contour and size of the shell (C. planulata excepted). The shells 

 occurring in the Becraft mountain Oriskany are of this persistent type, 

 of medium size, with strong posterior ridge and postcardinal depression, 

 with six to eight concentric lamellae, which are broad and free at the 

 edges and have their surface sculptured by fine lines, radial on the 

 postcardinal slope but en chevron over the umbonal ridge, again becoming 

 radial toward the middle of the shell. 



The species is represented in our collections by about a dozen specimens- 



