488 
PALEONTOLOGY OF NEW YORK. 
PALjEANATINA, Hall. 1870. 
P ALiEANATINA TYPA, HALL. 1870. 
PLATE LXXIX, FIGS. 26-28, 35-37. 
PalcEanatina typa, Hall. Prelim. Notice Lamellibranchiata, 2, p. 85. 1870. 
In part “ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 79, fig-s. 26-39. 1883. 
Shell short-soleniform, elongate, sub-elliptical; length twice the height; basal 
margin slightly sinuate in the middle, often nearly straight and sometimes 
gently curving. Posterior extremity abruptly rounded, often sub-truncate. 
Cardinal line straight, or slightly arcuate. Anterior end short, regularly 
rounded. 
Valves unequally convex, and apparently slightly gaping at both extrem¬ 
ities. Left valve somewhat gibbous in the umbonal region. Eight valve 
depressed-convex. 
Beaks in advance of the anterior third, appressed, rising but little above 
the hinge. Cincture very broad, undefined, affecting the lower half of the 
valve, producing a broad sinuosity in the margin. Umbonal slope obtusely 
sub-angular, extending to the post-inferior extremity. Cardinal slope nearly 
Hat or slightly concave, with a narrow fold developed near the cardinal line. 
Surface marked by fine concentric striae, which are frequently irregularly 
fasciculate on the basal portion of the shell. 
Four specimens measure respectively 16, 20, 28 and 31 mm. in length, 
and 7.25, 10, 14 and 15 mm. in height. 
The shells of this species vary considerably in form and expression. The 
umbonal ridge and the post-cardinal fold are variously developed, the umbonal 
slope being often scarcely angular, and the fold on the cardinal slope some¬ 
times obsolete. The cincture is also sometimes excessively developed, produc¬ 
ing a deep and broad sinuosity in the margin. But few specimens of the right 
valve have been observed ; these are depressed, the umbonal slope subdued, the 
beaks inconspicuous and without any evidence of a fold on the cardinal slope. 
Formation and locality. In the conglomerate of the Chemung group, at Port- 
ville, Cattaraugus county, N. Y. 
