
New and Little Known American Paleozotc Ostracoda. 133 
slightly depressed. Sulcus central, including a thin, sharply- 
defined mesial ridge. Surface smooth. 
Size: Length, 1.14 mm.; height, 0.58 mm. 
The thin mesial ridge is a peculiar feature. In other respects 
the species might be compared with P. humilis and paucipunctata, 
}-anad H. 
Position and locality: Upper beds of the Cincinnati Group, 
Jefferson County, Ky. The specimen illustrated is the only one 
seen. 
PRIMITIA MILLERI, N. sp. 
PlaleATS, Figs. 2a, 2b, 2c. 
Valves broad-ovate, the length and height respectively as two is 
to three. Ends subequal, the anterior sometimes slightly the nar- 
rowest. Free edges with an unusually narrow rim. Dorsal 
margin straight but short. Sulcus narrow, well impressed, not 
extending much over one-fourth of the height of a valve from the 
dorsal margin; bending forward at its lower extremity. Surface 
rising higher and more abruptly on the posterior side of the sulcus 
than on the anterior. Point of greatest convexity very near the 
center of the posterior half. 
Surface very finely reticulate, the meshes regular, mostly hexag- 
onal, with a tendency to an arrangement in concentric lines 
-observable. 
Size: Length, 1.08 mm.; height, 0.76 mm. 
Primitia bivertex, Ulrich, and its varieties, some of which resem- 
ble this species, have a more or less well-developed node on each 
side of the sulcus, and their shells are smooth. The valves of the 
new species, so long as they are in a good state of preservation, 
are not likely to be confounded with any other known to me. 
The specific name is given for Mr. S. A. Miller, the author of 
the well-known work ‘‘ North American Geology and Palzontol- 
ogy.” He kindly loaned me the original examples of his Primitia 
cincinnatiensis, and in looking over the slabs for that form several 
valves of this species were also found. My own specimens are 
from Clarksville and Blanchester, O., from shales between two 
and three hundred feet below the top of the Cincinnati Group. 
