194 Cincinnati Society of Natural History. 
half; ventral edge gently convex, curving neatly up into the 
anterior curve which is the most prominent above the middle; 
back straight, without cardinal angles. Counting the marginal 
ridge of the elevated area, there are five longitudinal ridges in the 
anterior half. In the posterior half they become irregular. 
Size: Length, o.88 mm.; height, 0.53 mm. 
Var. LOCULOSA, mn. vat, liga: 
In this variety the back is short, and both the ends most 
produced in the lower half. The elevated area is divided into 
numerous small compartments by cross-bars. Length, 0.85 mm.; 
height, o.5 mm. 
Var. OBLONGA, n. var., figs. ga, b, c. 
In this variety the ends are subequal, the dorsal and ventral 
edges parallel or nearly so, and the elevated area divided up in a 
very irregular manner. Length, 1.21 mm.; height, o.7 mm. 
Though these varieties appear very distinct, I am confident that 
with sufficient material a complete gradation from one to the other 
could be established. Very likely O. énnarasont, Jones (Quart. 
Jour. Geol. Soc., Nov. 1890, p. 541,. pl. XX mies: gee 
the same horizon and locality, represents another form of the same 
species, with a shape near var. /oculosa, and the elevated area 
consisting of a spirally wound ridge. O. octoformts, from the 
Wenlock of England, is another variable species, Prof. Jones 
having designated no less than seven distinguishable varieties. * 
Considerable variability may therefore be expected in species of 
this genus. | 
Position and locality: Devonian Bryozoa bed, Falls of the Ohio. 
OCTONARIA OVATA, Nn. Sp. 
Plate XVI, Figs. 6a, 6b. 
Size: Length, 0.75 mm.; height, 0.48 mm.; thickness, 0.45 mm. 
This is a true Ocfonaria, with shape and surface markings on 
the order of O. octoformis, Jones, but more nearly elliptical and 
symmetrical, and with the elevated area divided into more numer- 
ous pits. The right valve is somewhat smaller than the left, and 
straighter at the dorsal margin. 

*Ann. and Mag. N. Hist., ser. 5, vol. XIX, 1 sp. 404-407, June, 1887. 
