LAMELLIBRANCHIA TA. 
109 
Ligamental area grooved. 
The largest specimen has an entire length of 16 mm., height 10 mm., 
hinge-line, to the imperfect posterior extremity, 12 mm. A smaller speci¬ 
men has an entire length of 14 mm., height 9 mm., hinge-line 15 mm. The 
smallest specimen measures 10 mm. in length of body and hinge-line, and 
6 mm. in height. 
In form and surface characters this species is quite unlike any other described 
from these rocks. In some respects it resembles A. eximia, fig. 1, pi. xxv; but 
has more extended wing and less elongate body. 
Formation and locality. In the Marcellus shale at Littleville near West Avon, 
Livingston county, N. Y. 
Actinopteria Doris, n. sp. 
PLATE XVII, FIG. 4. 
Actinoptena Leander, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 17, fig. 4. Jan., 1883. 
Shell small, sub-rhomboidal; body obliquely sub-ovate; length a little greater 
than the height; margins regularly rounded, sloping abruptly from the 
upper part of the posterior side to the beak. 
Left valve depressed-convex. Right valve unknown. 
Hinge-line straight, about equal to the length of the shell (imperfect in the 
specimen described). 
Beak depressed, inclined forward, situated at the anterior third of the 
hinge. Umbonal region not defined, subtending an acute angle. 
Ear not observed. Wing large, flat, not distinctly defined; margin concave; 
extremity acute. 
Test thin, marked by regular, equal, rounded radii, with wider flat inter¬ 
spaces, and sometimes with obscure intermediate rays. The wing shows 
finer rays, somewhat crowded at its junction with the body. The fine, con¬ 
centric lines of growth are stronger on the anterior of the valve, giving a 
cancellate aspect to the surface. 
