118 Cincinnati Society of Natural Fiistory. 
dorsal nodes or short, vertical ridges, and the sickle-shaped mar- 
ginal ridge, which I regard as characteristic of the genus. A 
variety of D richardsoni, differing from the typical form of the 
species mainly in the more regular character of the superficial 
reticulation of the test, occurs at Oakville, Ontario, in purple 
shales, referred by the Canadian geologists to the Hudson River 
Group. It might be called var. canadensis. 
The species of this genus are either few and very variable, or 
they are numerous and distinguished by slight differences. 
According to the view adopted, the forms named amp/a, elongata, 
nitida, and macer will be regarded either as distinct species or all 
as varieties of D. crassinoda. A moderate and perhaps the proper 
view would be to place D. mitida and D. macer as varieties of PD. 
crassinoda, and LD. elongata as a variety of D. ampla. 
Another species occurs in the Trenton shales of Minnesota. In 
this the marginal ridge is developed only along the ventral bor- 
der. It will be described shortly, with other Ostracoda from the 
Northwest, in a bulletin of the Minnesota Academy of Sciences. 
DEPRANELLA CRASSINODA, N. sp. 
Plate VILL, fivess 1a, 0 ace 
Valves sub-elliptical, dorsal edge straight, one-fifth shorter than 
the greatest length of the valves. Ends equally convex, rounding 
gently into the less convex outline of the ventral margin. Posterior 
and ventral margins very thick, rising at once into the strongly 
elevated, narrow marginal ridge. Four nodes rise above the gen- 
eral level of the but little convex space included between the dor- 
sal edge and the marginal ridge. Three of these are on the 
anterior half of the valve; one small one, situated near the antero- 
dorsal angle, projects slightly beyond the dorsal margin. A second, 
much larger and very prominent node or ridge, extends from the 
dorsal margin half the distance to the ventral or marginal ridge. 
It has two apices, one of them projecting dorsally over the margin. 
Between this and the ventral ridge is another, crescent-shaped and 
only moderately high, but sharply defined, that extends from near 
the middle of the valve in a course nearly parallel with the antero- 
ventral margin. The fourth node, situated within the posterior 
half of the valve, is, more properly speaking, a strong ridge, 
