288 
PALEONTOLOGY OF NEW YORK. 
end to the post-basal extremity, abruptly recurving and extending thence in 
a nearly direct line to the cardinal margin; cardinal margin nearly straight. 
Anterior end short, rounded, without any indication of limitation by a sinus 
or otherwise. 
Valves moderately convex, scarcely gibbous in the umbonal region. 
Hinge-line straight, extending about half the length of the shell. 
Beaks sub-anterior, small, closely appressed, rising but little above the 
hinge-line. Umbonal region defined, sub-angular; the slope straight and 
rigid, extending from the beaks to the post-basal extremity. 
Test thin, marked by fine concentric striae, which are rarely fasciculate 
and elevated into ridges. Interior unknown. 
A medium-sized specimen has a length of 41 mm., and a height of 22 mm. 
A smaller specimen measures 30 mm. in length and 17 mm. in height. 
This species bears some resemblance to M. subalata, but is less alate on the 
posterior slope; the umbonal ridge is more direct, the post-basal extremity is 
directed more downward, basal margin more regularly convex and without 
evidence of a sinus. 
The original reference of figs. 10 and 11 of plate xli to this species is 
erroneous, those figures representing the Chemung variety of M. subalata. 
Formation and localities. In the sandstones of the Chemung group, near 
Angelica; and at Rock creek, Alleghany county, N. Y. 
Modiomorpha recurva. 
PLATE XLI, FIG. 17. 
Modiomorpha recurva, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 41, tig-. 17. 1SS3. 
Shell of medium size, ovate-sub-cuneate; length about twice the height; basal 
margin regularly curving to the anterior and posterior extremities. Posterior 
end acute, recurving very abruptly toward the cardinal line. Cardinal margin 
arcuate or nearly straight.' Anterior end short, abruptly rounded, limited 
posteriorly by a very shallow and undefined sinus (which is much too strongly 
represented in the figure). 
