PRODUCTELLiE OF THE CHEMUNG- GROUP. 
183 
This species bears some resemblance to the more extreme forms of Productella 
shumardiana of the Hamilton group, but it is a larger and stronger shell and 
marked by strong concentric wrinkles. The material at my command is not suffi¬ 
cient to make full comparisons. 
Geological formation and localities. In the. Chemung group, at Jasper in Steu¬ 
ben county, and south of Cadiz. 
Productella Malveata (n. s.). 
PLATE XXYI. 
Shell subovate or subhemispheric; the hinge-line about equalling, or 
sometimes a little greater than the width of the shell below. 
Ventral valve varying from moderately convex to extremely gibbous or 
ventricose; the greatest elevation being in a vertical line from a point 
just below the hinge-margin when the shell lies with the opening of 
the valve downwards, leaving the longest curve of the outline between 
this point and the front. The umbo is prominent, with the apex closely 
incurved over the hinge-line. Between the umbo and the cardinal 
angles the outline is abruptly sloping, or sometimes so depressed as to 
leave a concave outline at the sides of the umbo. The ears are broad 
and not strongly defined. In well-marked specimens there is a sinus, 
which is wider and well-defined on the lower two-thirds of the valve, 
and can be traced to the umbo. 
Dorsal valve moderately concave, and marked by an elevation on the 
lower half of its length, corresponding to the depression in the ventral 
valve. 
The surface of the ventral valve (judging from the casts) has been essen¬ 
tially free from striae, except the lines of growth. The ears are marked 
by two or three of more wrinkles and as many spines, while the body 
of the shell shows no indications of spines till we approach the margin, 
where there are or two or three rows of scattered spiniferous tuber¬ 
cles. The dorsal valves examined are not in a condition to enable us 
to determine whether fossets have existed, corresponding to the spines 
of the ventral valve. 
