S98 PALEONTOLOGY OF NEW-YORK. 



Geological formation and localities. This species occurs in the Hamilton group 

 at Burchard's quarry near Hamilton in Madison coimty, and is of frequent occur- 

 rence at Delphi falls in Onondaga county, and near Kelloggsville in Cayuga county, 

 whence I have formerly received it from Prof. Hopkins of Auburn. It is also found 

 in some other localities, and a single specimen from Thunder bay in Michigan is 

 of this or a closely allied species. 



Crjptonella (Terebrafula) eudora (n.s.). 



PLATE LXI. 



Shell broadly ovate, rounded in front ; apex obtuse. 



Ventral valve gibbous in the central and upper part, moderately convex 

 in the lower part, and sometimes flattened towards the front ; tapering 

 abruptly to the beak, which is obtuse, little extended beyond the 

 opposite valve, slightly incurved, and truncated by a rounded foramen. 



Dorsal valve depressed-convex, often gibbous in the middle above ; beak 

 incurved into the cavity below* the deltidial plates. 



Surface concentrically striate, with crowded lamelliform ridges towards 

 the sides and front. Shell-structure punctate. 

 The prevailing length is from one inch to nearly an inch and a half • 



the width, from three-fourths of an inch to an inch and a quarter. The 



separated dorsal valves are often of equal length and width. 



This species is proportionally broader than the prevailing forms in the Hamil- 

 ton group, though varying little from some specimens of the C. plantrostra, 

 which has a more extended beak and flattened cardinal slopes. 



Geological formation and localities. This species occurs in some dark argilla- 

 ceous sandstones in the Chemung group, near Ithaca, whence most of the speci- 

 mens have been received. It is found also at Chemung-narrows, Chemung county, 

 New- York. Specimens of similar form and proportions occur in the Waverly 

 sandstone of Licking county, Ohio ; and a specimen collected by Mr. Whitfield 

 at Rockford, Iowa, has essentially the same form and proportions. 



Collections made near Ithaca, while these pages are going through the press; 

 show the species to be comparatively abundant in some calcareo-arenaceous beds, 

 which, in their weathered decomposing portions, have left the casts of the 

 interior. 



