126 
PALEONTOLOGY OF NEW YORK. 
a conspicuous difference between the two. In the casts, faint impressions 
Of the revolving strias are usually preserved. 
The specimen figs. 20-22 is a cast of the interior, of remarkably rounded 
form, and showing a slight sinus on the left beneath the apex. The dorsum 
in fig. 22 is improperly represented as evenly convex, while there is a slight 
angularity visible in the specimen. 
Formation and localities. In the coarse shales of the Hamilton group at 
Hamilton, and at Pratt’s Falls in Madison county, N. Y. 
PORCELLIA, Leveille. 
PORCELLIA IIeRTZERI. 
PLATE XVI, FIG. 24. 
Porcellia Hertzeri, Hall. Illustrations of Devonian Fossils : Gasteropoda, pi. 16. 1876. 
Shell discoid. Volutions about four, very gradually enlarging, the last one 
rounded on the back, becoming ventricose towards the somewhat obovate 
aperture; dorso-lateral margin subangular, nodose, and sloping thence to 
the ventral margin; umbilical depression broad and shallow; the dorsal 
margin preserving evidence of a deep sinus. 
The finer surface-markings are unknown. The dorso-lateral margin is 
marked by distinct elongate nodes, and the sloping ventral sides preserve some 
remains of similar markings. 
The only specimen of the species known to me has a length of about one 
inch and a quarter, with a width of one inch. It resembles in form the 
European P. puzo, but the elongate nodes of the dorso-lateral margin present a 
very characteristic distinction. 
Formation and locality. In limestone of the Upper Helderberg group in Dela¬ 
ware, Ohio. The species has been communicated by Rev. Mr. Hertzer, 
of Louisville, Ky., formerly of Columbus, Ohio. 
