256 Thikty-fifth Report ox the State Museum. 



are about 20 in number. On the right valve the radii are repre- 

 sented by obscure, undulating, unequal striae. The ears show the 

 same surface markings. Cartilage-pit small. Ligamental area 

 thickened, with about eight flat, longitudinal lines extending to the 

 extremities of the hinge. 



A left valve measures 62 mm. from the anterior ear to the postero- 

 basal margin ; from the extremity of the beak the height is 55 mm., 

 and the length, parallel to the hinge, is about 54 mm. ; hinge-line 

 27 mm. The right valve is imperfect, but it 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 sinus. 



Formation and locality. In the slates of the Chemung group, at 

 Chemung Narrows, Chemung county, N. Y. 



Lyriopectest Priamus. 



Lyriopecten Priamus, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explana- 

 tions : 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 symmetric- 

 ally 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 de. 

 fined. 



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 sub- 

 dued and finer. Ligamental area 2.5 mm. wide in mature speci- 

 mens, and marked by numerous sharp, elevated, parallel, longitu- 

 dinal striae extending to the extremities of the hinge-line. Cartilage- 

 pit triangular, narrow, situated at the apex of the beak, and ex- 

 tending 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 



