LAMELLIBRANCHIA TA. 
29 
Aviculopecten signatus. 
PLATE VII, FIG. 24. 
Avicnla? signata. Hall. Geolog-. Surv. N. Y.: Rep. Fourth Dist., p. 265. 1843. 
Aviculopecten signatus. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 7, tig-. 24. Jan., 1883. 
Shell small, obliquely sub-elliptical, the longest diameter making an angle of 
about 45° with the hinge-line; height and length nearly equal. 
Left valve depressed, slightly convex. Right valve unknown. 
Hinge-line straight, length more than two-thirds the length of the shell, 
extending in front as far as the anterior margin. 
Beak very obtuse, rounded, depressed, directed forward, situated near the 
centre of the hinge. 
Ears triangular, sub-equal, flat. Anterior ear separated from the umbo by 
a sulcus; margin convex; extremity rounded. Byssal sinus moderately deep. 
Posterior ear not well-defined; margin slightly concave; extremity obtuse- 
angular. 
Test conspicuously marked by fine, regular, lamellose concentric lines, and 
a few irregular, radiating, indented striae. 
Interior characters not observed. 
The original of this species is 11 mm. in length and height; the hinge¬ 
line 8 mm. 
This species is distinguished by the oblique, elliptical outline of the body of 
the shell, the depressed, obtuse beak, and the well-defined concentric striae. 
Formation and locality. In the Chemung group at Rockville, Alleghany 
county, N. Y. 
Aviculopecten Caroli. 
PLATE IX, FIG. 5. 
Aviculopecten Caroli, Winchell. Proceedings Acad. Nat. Sci., Phila. 1863. 
Aviculopecten Caroli, (Winchell) Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 9, fig. 5. 
Jan., 1883. 
Shell small, sub-circular, not oblique, length and height equal; basal margin 
regularly rounded. 
