398 
PALAEONTOLOGY OF NEW-YORK. 
Geological formation and localities'* This species occurs in the Hamilton group 
at Burchard’s quarry near Hamilton in Madison county, 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. 
Cryptonella (Terebratula) 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. jplanirostra, 
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 Chemurig-narrows, Chemung county, 
New-York. Specimens of similar form and proportions occur in the Waverly 
sandstone of lacking county, Ohio ; and a specimen collected by Mr. Whitfield 
at Bockford, 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. 
