4 PALEONTOLOGY OF NEW YORK. 



" Monotis princeps. — Sla-U fonvt-x, (k-pressed ; car small, oiuarginate ; radiating 

 stria) numerous ; rugose, profound. Length about 3 inches. 



" Locality, Cazenovia." 



Mr. C<j.\KAi)'s de.sorii)tion of Avicula parilis is as follows (Jour. Acad. Nat. Sci. 

 Phila., Vol. VIII, p. 2.!U. 1842): 



•• Avicula parilis, pi. 12, fig. 0. — Upper valve Ihit ; lowei- valve plano-convex; 

 surface with numerous, equal, filiform, prominent radii ; w ings angulated at 

 tip. the anterior one most acute, and nearly eipial in length to the j)osterior 

 wing ; apex not elevated above the hinge line ; anterior, posterior, and basal 

 margins forming an uninterrupted arched or rounded outline. 



" Localilij. Cazenovia, Madison county. New York. Upper Silurian shale. 



" A beautiful and common sjiecies, the larger valve much resembling a 

 Pecten. 



"The Mo.NOTis j9rmce/)4-, of the Geological Reports of New York, is probably 

 the same sliell. 



" The Hat valve is represented on the plate." 



Formations and localities. \\\ liiiK'stone refericil to tlie age of tln' Upper 

 Ilelderberg group (Corniferous limestone), at Sandusky, Delaware, and near 

 Columbus, Ohio; ami also at the Falls of the Ohio. 



In the coarser shales of the Hamilton group, at numerous localities in the 

 eastern and central portions of the State ; in the upper soft calcareous shales 

 of the group at Moscow. Livingston county, N. Y., and very rarely in the 

 western extension of the group. 



AVICULOPECTEN PECTENIFORMIS. 



i'l.ATE I, KIG. n. 



AririiJn jMirtenl/nnniii. CoxnAD. Journal Aoiul. Nut. Sci. Phila.. vol. 8, p. 240. 1842. 



Ariculoperleii i>ecUni/oriais, (Co.nkau) Hall. Pal. N. V., vol. v, pt. 1. Plates an.l Kxplaiiatiou.>i : PI. 1, ti;,'. 



9. Jan., 1883. 



Shell siil)-ovate oblifpie to the hinge-line ; length equal to the height ; anterior 

 aM<l ba.sal margins regularly rounded, the body of the shell extending in a 

 nearly straight line from the po.stero-lateral margin to the beak. 



Left valve convex, retiching its greatest convexity at about one-third the 

 length of the valve from the beak. 



