PALEONTOLOGY OF NEW YORK. 
M 
only one of the genus yet found in the Schoharie grit. It differs from 
A. mnricata in its narrower and more oblique body and shorter wing, as 
measured along the post-cardinal slope. 
Formation and locality. In the Schoharie grit, at Schoharie, N. Y. 
Actinopteria muricata. 
PLATE XVII, FIGS. 1-3. 
Avicula muricata, Hall. Geol. Surv. N. Y.: Rep. Fourth Dist., p. 181. 1843. 
Pteronites muricatus, Hall. Cat. Am. Pal. Foss.: S. A. Miller, p. 202. 1877. 
Actinopteria muricata, Hall. Pal. N. Y., vol. v, pt 1. Plates and Explanations: PI. 17, tigs. 1-3. Jan., 1883. 
Shell small, sub-rhomboidal; body sub-ovate, very oblique; length one-third 
greater than the height; margin rounded below, turning abruptly backward 
on the posterior side, and extending in a direct line to the beak. 
Left valve convex. Right valve unknown. 
Hinge-line straight from the beak to the posterior extremity, sloping 
downward on the anterior side; entire length greater than that of the body 
of the shell. 
Beak acute, arching over the hinge, inclined forward, situated at the 
anterior third of the hinge-line. Umbonal region subtending an acute angle. 
Ear broad-triangular, separated from the body of the shell by a broad 
undefined sulcus which is limited by a strong sub-angular fold extending 
from the beak, and by the deep rounded byssal sinus; margin convex; 
extremity obtuse. Wing flat, triangular, defined by having more subdued 
surface rays; margin deeply sinuate; extremity mucronate. 
Test thin, marked with from eight to twelve strong, filiform rays, with 
finer intermediate ones in the broad, flat interspaces. The rays on the wing 
are somewhat subdued. Surface crossed by fine concentric lines of growth, 
which, at intervals, are crowded and raised into lamellae, and on the rays are 
produced into tubular spines. These spines are seen only in the better pre¬ 
served specimens, and appear in the casts as elongate elevations upon the 
rays. The concentric striae are conspicuous in the anterior sulcus. 
Interior unknown. 
