4 
132 Cincinnati Soctety of Natural History. 
Position and locality: This species has till now been collected 
only at Savannah, IIl., in beds equivalent to the middle or upper 
portion of the Cincinnati Group. The specimens are associated 
with numerous minute bryozoa, of which Z7vematopora (?) nitida, 
Ulrich, and Sveptropora facula, Ulrich, are the most noteworthy. 
PRIMITIA CINCINNATIENSIS, S. ‘A. Miller. 
Plate X, Figs. 5a, 56, 6a, 66 and 6c. 
Beyrichia cincinnatiensis, S. A. Miller, Cin. Quart. Jour. Sci., Vol. 
11s 350: 
The original description and figure of this species are too indefi- 
nite for its identification, and, furthermore, since the species is 
interesting in this, that in some of its varieties a departure from 
Primitia toward Kledenia and Beyrichia is indicated, it has appeared 
desirable to illustrate its peculiarities. 
Fig. 6@ represents the right valve of an average example, in 
which the flange is pronounced, the ends sub-equal, the sulcus 
deep, and the tumid regions on each side of it almost equal. 
A left valve of a larger example, fig. 5¢, shows some marked 
differences. The flange is narrow, and the tumid region in front 
of the strong sulcus has become separated to such an extent as to 
suggest the median tubercle of K/ewdenia and Beyrichia. Of course, 
this departure from the typical form is very rare. 
Length,o6 mm.; height, 0.38 mm. 
Size :— £ Spe NOR ahah ook es O.AMG IS 
ete Ooze {< OSG aes 
Position and locality: Upper half of the Cincinnati Group. 
Mr. Miller collected his specimens near Weisburg, nearly three 
hundred feet below the Upper Silurian, while mine were collected 
at Clarksville, Ohio, in shales at least one hundred feet higher. 
PRIMITIA MEDIALIS, n.-sp. 
Plate X, Figs. 7a and 70. 
Carapace oblong, most convex in the ventral and posterior 
regions; dorsal margin straight, but not terminating sharply at 
the ends; ventral outline evenly convex, rounding gently into the 
ends, of which the posterior is the most blunt. Dorsal slope 


