314 Cincinnati Society of Natural History. 
small, pointed and extending beyond the cardinal area. Ventral valve 
most convex near the beak, sloping off wedge-shaped toward the front, 
and very rapidly, at first, toward the posterio-lateral sides, but flatten- 
ing out before reaching the margins. The beak is elevated, sharp, 
slightly incurved, and extends beyond the beak of the opposite valve. 
The length of the linear area is about half the width of the shell. 
The surface is ornamented by numerous fine, round, radiating strie, 
which increase by implantation, and are crossed by several strong, 
concentric, imbricating lines of growth, and intermediate finer concen- 
tric lines. This species, in its surface markings, resembles O. vanuxemi 
from the Devonian, but the striz are finer and more numerous, and it . 
may readily be distinguished from other species found in rocks of its 
own age. 
SPIRIFERA TEMERARIA, 0. Sp. 
Plate VII., fig. 9, ventral view ; fig. 9a, dorsal view: fig. 9b, front view. 
Shell small, transversely subelliptical, moderately gibbous, hinge 
line less than the width of the shell, and cardinal extremities rounded. 
Dorsal valve convex from back to front ; mesial fold convex, much 
elevated at the front, while at the anterior sides of the mesial fold, the 
shell is rapidly curved down, and produced to meet the truncated ex- 
tension of the opposite valve on each side of the sinas ; the beak is of 
moderate size, and arched over the linear area. Ventral valve, gib- 
bous in the umbonal region, and sloping to the front and sides ; the 
sinus, commencing with a shallow, rounded depression in the umbonal 
region, becomes more and more strongly defined, and terminates in a 
deep, somewhat angular, and much produced extension in front. The 
beak extends beyond the beak of the opposite valve, and is incurved 
over the area, which is almost linear. 
The surface is ornamented with very fine Sue lines, which are 
crossed by numerous fine concentric lines, and a few stronger imbri- 
cating lines ofgrowth. There is only asingle specimen of this species 
in the collection, and it is therefore supposed to be a rare form—hence 
the specific name. 
SPIRIFERA NOVAMEXICANA, 0. Sp. 
Plate VII., fig. 10, ventral view; fig. 10a, dorsal and cardinal view ; fig, 100, front view. 
Shell more or less gibbous, transverse, triangular, and having the 
cardinal angles extended into mucronate points. The dorsal valve is 
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