;,l PALEONTOLOGY OF NEW YORK. 



The righl valve is imperfect, but appears to have been more circular in 

 outline than the left. 



This species is characterized l>\ its form, surface ornamentation, and marked 

 resemblance between its righl 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, i. 



Lyriopecten Priamus, Hall. Pal. N. V.. vol. v, pt. 1. Plates and Explanations: PI. 10, tigs. 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, suit-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 41) strong, rounded, irregular radii with narrow 

 interspaces, crossed by fine stria? 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 apes of the beak, and extending to the margin of the hinge. 



One large specimen, which is a cast of the interior, measures ~2 mm. in 

 height, 70 mm. in length ; hinge-line 32 mm. A smaller specimen, showing 



