OF DENISON UNIVERSITY. 
145 
4. Discina nitida^ Sow. (Plate II, Figs. 8-9.) 
(Discina meekiana, Whitfield. ) 
This species, if not identical with the European, is a very close 
vicarious form and ought probably to be ranked as a geographical va- 
riety. Some of our specimens show the radiating markings figured 
by Davidson ( 1 . c. supl. .Pl. XXX), and differ chiefly in the somewhat 
more central position of the beak. 
5. Edmondia (?) rcflexa^ Meek, (Plate XIV, Fig. 21.) 
Only the exterior of the valves has been seen. 
6. Pleurophorus vnmaturus ^ sp? n. (Plate XIV, Fig. 17.) 
There would seem to be constant differences between the small 
compact form referred to on page 35 and P. subcostaius, yi. and W., 
which proves to be very abundant and typical. A considerable series 
of the latter has been obtained with constant characters. 
While far from sure that the smaller form is not the young, it may 
be best to distinguish it. The lower anterior margin is more abruptly 
curved and the lower margin convex. The width is over one-half the 
length, while in P. subcostatus it much less. The radiating striae also 
cover a larger part of the shell, which is more convex. - 
7. Placunopsis carhonaria^ M. and W., (Plate XIV, Fig. 27.) 
A- specimen from the locality ofMeek’s P. recticardinalis is, like 
the one figured in the O. Pal., a cast of the interior, but has the beak 
nearer the posterior rounded ear. The markings seem to be char- 
acteristic and not accidental. Meek’s conjecture of the identity of 
these species seems correct. 
8. Cf. Pseudomonotiis radialis. Meek, Pal. Neb., Plate IX, 
Fig. 3. (Plate XIV, Fig. 26.) 
A single left valve resembles that figured by Meek, but has 
coarser distant radiating lines with finer striae implanted between. 
The posterior wing is imperfect at the very top. The generic refer- 
ence is doubtful. 
9. Schizodus curfus, M. and W. (Plate XIV, Fig. 20.) 
This small species is represented by both valves in connection, 
which agree quite as well with S. rossicus, however, as the species to 
which they are referred. 
10. Schlzodus subcircularts , Her. (Plate XIV, Fig. 18, ) a cast. 
11. Avicula {Gervillia) ohioense, Her. (Plate XIV, Fig. 22.) 
