LAMELLIBRANCHIA TA. 
4G5 
volume. It is distinguished by the central position of the beaks, the emargi- 
nate posterior end and the peculiar character of the surface radii. 
Formation and localities. In the shales of the Hamilton group at Fultonham, 
Schoharie county, and on the shores of Skaneateles, Otisco, Cayuga, Seneca 
and Canandaigua lakes; at Smyrna, Chenango county, and in other places in 
the State of New York. 
CIMITARIA, Hall. 1870. 
ClMITARIA CORRUGATA. 
PLATE LXXVII, FIGS. 1-4. 
Cypricardites corrugata , Conrad. Jour. Acad. Nat. Sci., vol. viii, p. 244, pi. 13, fig. 6. 1842. 
Cimitaria corrugata (Conrad), Hall. Prelim. Notice Lamellibranchiata, 2, p. 67. 1S70. 
“ “ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: Pl. 77, figs. 1-4. 
1883. 
Shell large, sub-falciform, extremely elongate, with the cardinal line curving 
upward at the extremities ; length three times the height; basal margin 
regularly curving, with a gentle sinuosity near the anterior end. Posterior 
extremity vertically or somewhat oblicpiely truncate. Cardinal line concave, 
essentially parallel with the basal margin. Anterior end obliquely truncate 
above and rounded below into the basal margin. 
Valves depressed-convex in the lower and posterior portions, more convex 
and somewhat gibbous in the umbonal region. 
Beaks at about the anterior sixth, prominent and incurved. Umbonal 
slope angular, marked by a distinct fold, which extends to the post-inferior 
extremity. Post-cardinal slope comparatively wide, marked by one, or 
several radiating folds, which are sometimes obsolescent. Cincture dis¬ 
tinct, extending obliquely backward from the beak to the base, giving a 
sinuosity to the margin. 
Surface marked by numerous fine concentric striae. The body of the shell 
is also marked by irregular concentric undulations, which are sometimes 
interrupted, giving the surface a rugose appearance. The undulations ter¬ 
minate upon the angular umbonal slope, the post-cardinal area being simply 
