54 
PALEONTOLOGY OF NEW YORK. 
The right valve is imperfect, but appears to have been more circular in 
outline than the left. 
This species is characterized by its form, surface ornamentation, and marked 
resemblance between its right valve and the lower valves of some species of 
the recent genus Anomia, in the flatness of the valve and deep byssal sinus. 
Formation and locality. In the slates of the Chemung group, at Chemung 
Narrows, Chemung county, N. Y. 
Lyriopecten Priamus. 
PLATE X, FIGS. 1, 2. 
Lyriopecten Priamus, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: pi. 10, figs. 1, 2. Jan., 1883. 
Shell large, transversely broadly elliptical or ovate, wider below; transverse 
axis normal or very slightly oblique to the hinge-line; height less than one- 
tenth greater than the longitudinal diameter; margins regularly rounded. 
Left valve moderately and symmetrically convex. Right valve unknown. 
Hinge-line straight, sub-central; length about one-half the longitudinal 
diameter of the shell. 
Beak obtuse, rounded, oblique, anterior to the transverse axis, not rising- 
above nor extending as far as the hinge-margin. 
Anterior ear small and undefined. Posterior ear broad-triangular, flat; 
margin concave; extremity angular. Byssal sinus not defined. 
Test marked by about 40 strong, rounded, irregular radii with narrow 
interspaces, crossed by fine striae of growth. The rays are often composed 
of fascicles of thread-like striae, and bifurcate at some point of their length. 
On the posterior ear the rays are subdued and finer. 
Ligamental area 2.5 mm. wide in mature specimens, and marked by 
numerous sharp, elevated, parallel, longitudinal striae extending to the 
extremities of the hinge-line. Cartilage-pit triangular, narrow, situated at 
the apex of the beak, and extending to the margin of the hinge. 
One large specimen, which is a cast of the interior, measures 72 mm. in 
height, 70 mm. in length; hinge-line 32 mm. A smaller specimen, showing 
