514 
PALAEONTOLOGY OF NEW YORK. 
M 0 D I E L L A , Hall. 1883. 
Modiella pygm^ea. 
PLATE LXXVI, FIGS 9-20. 
Pterinea pygmcea, Conrad. Jour. Acacl. Nat. Sci., Phila., vol. viii, p. 251, pi. 13, fig-. 15. 1842. 
Cypricardinia pygmcea (Conrad), S. A. Miller. Cat. Am. Pal. Foss., p. 188. 1877. 
Modiella pygmcea (Conrad), Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 76, figs. 9-20. 
18S3. 
Shj;ll small, obliquely obovate; length one-third greater than the height. 
Basal margin arcuate anterior to the middle, broadly and distinctly curving 
to the post-inferior extremity. Posterior margin obliquely and broadly 
curved. Cardinal line distinctly arcuate, reaching beyond the middle of the 
length of the shell. Anterior end short, auriculate, limited by a depression 
extending from just anterior to the beak to the basal margin and producing 
a more or less distinct sinus. 
Valves very convex in the middle and upper portions of the shell. 
Beaks sub-anterior, small, closely appressed and incurved. Umbonal 
slope not distinctly limited, rather prominent, arcuate, extending to the post¬ 
inferior extremity. Along the middle of the cardinal slope there is some¬ 
times a depression extending to the posterior margin. 
Surface marked by fine concentric striae, crossed by curving, radiating 
striae which are more distinct on the hod}^ of the shell just posterior to the 
sinus. In well-preserved specimens the junctions of the radii with the con¬ 
centric striae are elevated into minute pustules. 
Muscular impressions and pallia! line distinctly marked. Hinge-line with 
a narrow groove posterior to the beaks. 
Three specimens measure respectively 10, 14 and 15 mm. in length, and 
7, 9.5 and 10 mm. in height. 
The shell has the general form and external characters of a Modiola, with a 
constriction on the antero-basal margin indicating the place of a byssal sinus. 
Formation and localities. In the shales of the Hamilton group at Pratt’s falls, 
Onondaga county, and on the shores of ‘Skaneateles, Otisco and Cayuga 
lakes, N. Y. 
