IIo Czncinnats Society of Natural /1istory. 
CTENOBOLBINA ALATA, N. Sp. 
Flate VII, Figs. 4 a, b, ¢. 
Carapace strongly convex, sub-oblong, obliquely ovate, straight 
on the back, elliptically rounded below, the ends strongly rounded, 
with the anterior one much the narrowest. Sulci very oblique, the 
posterior one. well marked, the anterior scarcely perceptible. A 
strong wing-like process developed from the ventral prolongation 
of the anterior lobe. Flange well developed only in the older 
examples. Ventral and posterior edges very thick and concave 
beneath the flange; bordering the contact edges a series of blunt 
spines. Surface strongly granulose. 
Length, 1.32 mm.; Height, 0.71 mm.; Uhickmess, o 43imam: 
66 2.0 66 66 1.15 66 66 On72 66 
66 ZW 66 66 1.2 66 66 I.O (a 
Size 
The alate processes, when fully developed, impart a rather gro- 
tesque appearance tothis species. ‘They are, however, easily worn 
away or broken, and, moreover, seem to be a rather variable fea- 
ture, since in some examples, apparently in a good state of preser- 
vation, they are considerably smaller, and more spine-like than in 
those figured. In such cases the species is distinguished from C. 
ciliata and the closely related C. duryz, by the narrower anterior 
end, and greater obliquity of the valves. They are also more 
convex. 
Position and locality: Lower shales of the Cincinnati Group, 
at Cincinnati, Chio. The best examples were obtained from exca- 
vations along Brown Street. 
CTENOBOLBINA BISPINOSA, N. Sp. 
Flate VIL, Fig. 6. 
Carapace rather strongly convex, sub-oblong, obliquely ovate, — 
elliptically rounded below and straight at the dorsal edge. Posterior 
end wider and more abruptly curved into the ventral edge than 
the anterior. ree margins spinous, without flange, or with same 
very narrow. Surface of valves papillose. Anterior sulcus 
usually obsolete, the posterior one narrow, well defined, extending 
from the center of the dorsal margin in a slightly curved direction 
about two-thirds across the valve. Posterior lobe rounded; median 
and anterior lobes confluent. These conditions impart to the 
