212 PALEONTOLOGY OF NEW YORK. 



Lbptodbsma Corydon, n. sp. 



PL \TK \< .]!'■. 82 



Shell above the medium size, sub-rhomboidal ; body narrowing very rapidbj 

 toward the beak, oblique to the binge-Line at an angle of about 30°; length 

 less than twice the height; ante-byssal margin oblique, nearly straight, 

 slightbj impressed ai the sinus, broadly curved at the base and rounded on 

 the posterior extremity. 



Lett valve depressed-convex below and slightly gibbous on the umbo 

 (as preserved in thinly laminated shale). Right valve unknown. 



Binge-line straight, about equal to the greatest length of the shell. 



Beak sub-anterior, directed forward, little elevated above the cardinal line. 

 Qmbonal region moderately gibbous, subtending an acute angle. 



Anterior end narrow, rostrate, acute, extended, defined by a distinct, 

 shallow, byssal depression which produces a long, gentle curvature in the 

 margin of the valve. Wing narrow, joining the body at nearly the posterior 

 extremity ; margin abruptly recurved below and somewhat deeply concave a 

 little below the cardinal line : extremity forming a spiniform extension. 



Tesl thin, marked by \\i\e concentric striae, which are fasciculate on the 

 body at unequal distances, and sharply elevated and more distinct on the 

 wing. 



Interior unknown. 



A left valve of medium size has a length of 42 mm., height 2~) inn... 

 hinee-line about 40 mm. 



.— 



Compared with L. CI it us, the body of the shell is more elongate-ovate or 

 sub-spatulate, narrowing more rapidly toward the post-e\tremit\ ; the wing is 

 wider and the sinuosity less deep, its greatest depth being near the cardinal 

 line. 



Formation and locality. In the Chemung group. Kelly's creek. Tioga county. 

 1'a. 



