LAMELLIB RANCHI A TA. 
243 
The specimens show an oblique lateral tooth, with obscure indications of 
anterior teeth or folds. Ligamental area narrow, marked with fine parallel 
striae. 
A left valve has a length of 45 mm., height 50 mm., hinge-line, when 
entire, about 75 mm. A small right valve has a length 34 mm., height 
27 mm., hinge-line about 45 mm. 
This species is distinguished by the great and nearly equal extent of the 
hinge-line on both sides of the beak; by the peculiar form of the body of the 
shell; and by its surface characters, which are unlike any yet observed. 
Formation and localities. In the Chemung group at Franklin, Delaware 
county; and a right valve referred to this species is from a point four miles 
above Chenango Forks, Chenango county, N. Y. 
LIMOPTERA, Hall. 
Limoptera pauperata. 
PLATE XXVI, PIG. 5. 
Limoptera pauperata. Halt,. Prelim. Notice Lam. Shells, etc., pt. 2, p. 16. Dec , .1869. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 26, fig. 5. Jan., 1883. 
Shell large; body ovate, sub-erect; wing greatly expanded; height much 
greater than the length; basal margin broadly rounded; posterior side 
gently curving from the post-basal extremity to the beak. 
Left valve somewhat regularly convex from the umbo to the base. Right 
valve unknown. 
Hinge-line straight, longer than the greatest length of the valve. 
Beak of the left valve prominent, inclined forward, rising above the 
hinge-line, situated anterior to the middle of the body of the shell. 
Umbonal region moderately gibbous, abrupt on the anterior, and more gently 
sloping on the posterior side. 
Auricle and byssal sinus unknown. Wing large, triangular, not distinctly 
limited from the body, and extending nearly to the post-basal extremity of 
the shell; margin slightly concave; extremity abrupt (rectangular ?). 
