388 
PALAEONTOLOGY OF NEW-YORK. 
Surface marked by fine close concentric striae which are neatly rounded 
on well-preserved specimens, and at intervals are crowded into more 
prominent ridges. Shell-structure punctate. 
On cutting down a specimen of this species, it has been found to pos¬ 
sess a short simple loop, without appendage, as in Terebratula. 
The larger specimens are about three-fourths of an inch in length. 
The shell is readily dictinguished by its elongate form, moderate convexity, 
truncate or sinuate front, and median depression in the ventral valve ; features, 
which I have not observed in any other species in this geological formation. 
Geological formation and localities. This species occurs in the Upper Helder- 
berg limestone, at Columbus and Sandusky, Ohio ; and in the neighborhood of 
Cayuga, Canada West. 
Terebratula hanuonia (n. s.). 
PLATE LX. 
.Shell ovate or subspatulate, tapering somewhat abruptly to the beak, 
convex in the middle and compressed at the margin^. 
Ventral valve regularly arcuate from beak to front, moderately convex 
in the middle, a little gibbous above and depressed-convex or slightly 
concave towards the front, the upper part narrowing; the beak much 
extended, attenuate and arcuate, but not closely incurved; apex per¬ 
forate, the slope to the cardinal margin scarcely concave : deltidial 
plates large. 
Dorsal valve moderately convex, sometimes a little more prominent 
along the middle in the upper part, and depressed towards the front 
and sides. 
Surfa'CE marked by fine concentric lines of growth; the substance of 
the shell finely punctate. 
A well-marked specimen of this species has been cut down on the 
dorsal side, revealing the loop, the divisions of which extend for more 
than one-third the length of the dorsal valve; the angle of return being 
visible, but not the connecting portion. 
