PRODUCTELLiE OF TJIE CHEMUNG GROUP. 175 
Dorsal valve large, somewhat regularly and sometimes deeply concave, 
but with barely any indication of sudden deflection to the front. 
Surface of the casts of the ventral valves finely striate or puncto-striate 
longitudinally, the puncta more marked towards the base of the valve. 
The ears are strongly wrinkled, with the bases of several spines upon 
the folds; these wrinkles extend in obscure undulations across the body 
of the shell in its upper part. The entire surface is marked by narrow 
elongate fossets which indicate the places of the spines, the slender 
bases of which sometimes remain in the depression : in some indi¬ 
viduals, there are oval pustules in place of the fossets. There is no 
appreciable tendency to elongation of these pits or ridges towards the 
•front of the shell; nor does the surface become costate towards the 
margin, as those which I have referred to P. lachrymosa proper, from 
Chemung-narrows. 
The dorsal valves, associated in the same beds, are strongly wrinkled 
on the ears, with the folds faintly marked on the body of the shell, which 
is studded with numerous scattered shallow depressions corresponding to 
the spines on the opposite valve. The cardinal process is distinctly 
four-lobed. 
This is one of the largest forms among the Chemung species; and I am inclined 
to believe that it may ultimately be proved specifically distinct from P. lachrymosa. 
Geological formation and localities. In the light-colored sandstones of the Che¬ 
mung group, near Olean ; and in a similar rock at Conewango, and in some de¬ 
composing semicalcareous layers at Randolph and East-Randolph, Cattaraugus 
county, New-York. 
Productella speciosa. 
PLATE XXV. 
Prod'uctus speciosus : Hail, in Tenth Report on the State Cabinet, p. 176. 1857. 
Shell broadly ovate, subhemispheric; hinge-line less than the greatest 
width of the shell, the extremities obtusely angular. 
Ventral valve ventricose : umbo much elevated above the hinge-line, 
with the apex closely incurved, regularly arcuate from beak to base and 
more rapidly curving to the sides, abruptly depressed on the sides of 
the umbo, and concave between it and the narrow short ears. 
