PALEONTOLOGY OF NEW-YORK. 
Geological formation and localities. The original or type specimens of the spe¬ 
cies occur in beds of the age of the Hamilton group, at Thunder bay, Michigan. 
It is found in the same horizon at York in Livingston county, and at Hamburgh 
on the shore of Lake Erie. It has likewise been found at Waterloo, Iowa, by Mr. 
E. P. Whitfield. 
Terebratula elm (n.s.). 
PLATE LX. 
Shell ovate, arcuate on the ventral side; beak prominent. 
Ventral valve regularly arcuate from beak to base, gibbous in the mid¬ 
dle and above; umbo prominent; beak little incurved and broadly 
truncate by a rounded foramen, which is limited on the lower side by 
two large deltidial pieces. 
Dorsal valve regularly convex, the greatest convexity in the middle, 
where it is about equal to that of the opposite valve. The depth, width 
and length are as two, three and four-eighths of an inch. 
Surface concentrically striate, shell-substance punctate. 
Geological formation and locality. This species occurs at Waterloo, Iowa, in 
strata of the age of the Upper Helderberg or Hamilton group. Eeceived from Mr. 
O. St. John. 
Terebratula jucumla (n.s.). 
PLATE LX. 
Shell subcircular or very broadly ovate, the length and width about 
equal, regularly rounded below and abruptly narrowing above the 
middle. 
Ventral valve gibbous in the middle, curving regularly to the base and 
baso-lateral margins : beak obtuse, and incurved over the umbo of 
the opposite valve; apex truncated by a rounded foramen. 
Dorsal valve rather regularly convex, the greatest convexity a little 
above the middle, curving to the base and baso-lateral margins. 
Length of specimens, a little more than three-eighths of an inch. 
On cutting down from the dorsal side, the loop is visible, showing the 
terebratuloid character. 
