414 
PALAEONTOLOGY OF NEW YORK. 
Pholidops oftlata (n. s.). 
PLATE III, FIG. 10. 
Shell suborbicular, somewhat flattened on the upper margin, discoid or 
depressed convex; the length and width about equal; muscular area of 
the interior small, circular, and divided through the middle by a longitu¬ 
dinal septum. External surface unknown. 
In general aspect this species somewhat resembles P. armaria , but differs very 
materially in the form of the muscular impression. 
Geological formation and locality. In the shales of the Hamilton group, at Car 
ter’s Mills, four miles south of Aurora, Onondaga county, N. Y. 
Pholidops ? liiiguloides (n. s.). 
PLATE III, FIG. 11. 
Shell broadly ovate, with an obtusely pointed beak, which is apparently 
terminal. 
Surface covered by rather closely arranged, strongly lamellose concentric 
lines of growth, which reach the margin of the valve near the beak. 
Length of shell sixty-two hundredths of an inch; greatest width, fifty-six 
hundredths of an inch. 
This species differs from any of the described forms of the genus Pholidops in 
its terminal beak and subnacreous shell. There may be some doubt regarding the 
propriety of its reference to this genus, but at present no other group seems so well 
adapted to its reception. 
Geological formation and locality. In concretionary layers of the Hamilton 
shales, on Canandaigua Lake, New York. 
Strophomesia rhomhoidalis ? 
PLATE XV, FIGS. 15, 16. 
Specimens of shells having the characters of this species have been 
obtained among a collection from Mallet’s Creek, two miles north of York 
