26 PALEONTOLOGY OF NEW YORK. 



Ears eub-equal, broad-triangular, Hat ; margins slightly convex; extremities 

 rectangular, defined by a gentle .sinus, which is deeper below the anterior ear. 



Test marked by about 35 strong, rounded, radiating continuous plications 

 which are wider than the interspaces. These radii are absent on the ears. 

 The strise of growth are irregular and mark the entire surface of the shell. 



Internal characters not observed. 



A large specimen has a height of 58 mm., length GG mm., hinge-line 34 mm. 



This species differs from A. patulus in its shorter hinge-line, and the strong 

 rounded radiating plications. 



Formation and locality. In sandstone of the upper part of the Chemung 

 group at Meadville, Crawford county, Pennsylvania. 



AVICULOPECTEN DOLABRIFORMIS. 



PLATE VII, FIG. 21. 



Pevte.ii? dolabriformis, Hall. Geolog. Sui-v. N. Y. : Rep. Fourth Dist., p. 21!"). 1S43. 

 dviculopecten doiabriformis. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 7. 6g. 21. 



Jan., 1883. 



Shell small, sub-orbicular, slightly oblique ; height nearly equal to the length ; 

 margins regularly rounded, becoming more inflated and convex posteriorly. 



Right valve moderately convex. Left valve unknown. 



Hinge-line straight, central, more than two-thirds the length of the shell. 



Beak central, straight, obtuse, rounded, not rising above the hinge-line ; 

 umbo well defined by the rapid slope of the sides and the flatness of the 

 cars. 



Ears triangular, flat; margins slightly concave; extremities obtuse-angular. 

 Posterior ear of the right valve about one-third larger than the anterior. 

 Byssal sinus not marked. 



Test cancellate, marked bj fine radii and concentric strise, which char- 

 acters are also preserved on the ears. 



Internal characters not known. 



A right valve has a height of 11 mm., length 12 mm., and hinge-line 8 mm. 



