346 Thirty-fifth Keport on the State Museum. 



in its longer hinge-line, larger wing, and more acute beak, while the 

 body of the shell is narrower. 



In the volume of Plates and Explanations this species was referred 

 to L. Dekayi in the absence of the original specimen, which has since 

 been compared and found to belong to the Chemung group. 



Formation and locality. In a slaty sandstone of the Chemung group, 

 eight miles north of Binghamton N". Y 



Leiopteria linguiformis. 



Leiopteria linguiformis, Hall. Pal. N. Y.,vol. v, pt. 1. Unpublished. 



Shell above medium size, erect, sub-rhomboidal ; body elongate- 

 ovate, making an angle of about 60° with the hinge-line; length 

 equal to three-fourths of the height ; anterior margin nearly verti- 

 cal from the byssal sinus to below the middle of the valve ; basal 

 margin broadly rounded; post-basal margin rapidly curving into 

 the wing. Left valve convex above, depressed-convex below. Eight 

 valve unknown. Hinge-line straight, nearly equal to the length of 

 the shell. Beak acute, erect, prominent, rising above the hinge- 

 line. Umbonal region convex, subtending an acute angle. Ear 

 small, triangular, bending slightly downward, limited by a well- 

 defined byssal depression ; margin nearly straight ; extremity 

 rounded. Byssal sinus shallow. Wing broad-triangular, joining 

 the body below the middle of the post-cardinal slope, not strongly 

 limited ; margin concave ; extremity acute. 



Surface marked by concentric striae which are strongly lamellose 

 on the ear, the pallial margins and on the wing. Ligamental area 

 narrow, marked by two or three longitudinal grooves. Muscular 

 impression oval, situated near the middle of the post-cardinal slope. 



The specimen described has a length of 33 mm., height 42 mm., 

 and hinge-line 32 mm. 



This species differs from L. Chemung ensis in its more erect form, 

 and the ear is without the strong fold and marked sulcus of that 

 species ; the wing is also less extended and the margin less concave. 



Formation and locality. In the Chemung group in the valley of 

 Cayuta creek, Broome county, N. Y. 



Leiopteria Torreti. 



Leiopteria Torreyi, Hall. Pal. N. Y., vol. v, pt. 1. Unpublished. 



Shfll of medium size, rhomboidal, sub-falcate ; body narrow-ovate, 

 arcuate, oblique at an angle of less than 45° with the hinge ; height 

 equal to about two-thirds of the length ; anterior and basal margins 



