PLATE 1 
Fig. 1. Strophomena planoconvexa. A, C, D, pedicel valves; B, brachial valve. 
E, interior view of pedicel valve. F, view of hinge area, copied from Ohio Paleon- 
tology, vol. I, plate VI, Fig. 2 C. Cincinnati, Ohio. Base of Fairmount. 
Fig. 2. Stropho?nena planoconvexa. A, pedicel valve; B, brachial valve. One 
of a group of similar specimens, occurring in local collections at Wilmington, Ohio, 
and stated to have been collected in the Waynesville beds at Clarksville. They 
can not be distinguished in any manner from Strophomena planoconvexa, and 
apparently are typical basal Fairmount specimens from the vicinity of Cincinnati. 
Fig. 3. Strophomena sinuata. A, pedicel valve; B, C, brachial valves. Cin- 
cinnati, Ohio, from the middle part of the Fairmount. 
Fig. 4. Strophomena sulcata. A, B, brachial valves, differing in the coarseness 
of the radiating striae; C, interior of pedicel valve. A is much more sulcate along 
the anterior edge than is indicated by the figure. Dutch Creek, 4^ miles north- 
west of Wilmington, Ohio. Near top of Whitewater member. 
Fig. 5. Leptaena gibhosa. A, B, pedicel valves; radiating striae too fine to be 
indicated by the figure. C, interior view of brachial valve. Cincinnati, Ohio. 
Economy member of Eden. Type specimen, number 1114, James collection. 
Walker Museum at Chicago University. 
Fig. 6 A. Leptaena richmondensis-precursor . Pedicel valve. Arnheim, Ohio. 
Arnheim member. 
Fig. 6. B, C. Leptaena richmondensis . B, pedicel valve; C, brachial valve. 
Madison, Indiana. Waynesville member. 
Fig. 7. Plectamhonites rugosa-clarksvillensis. All specimens nine-tenths of 
natural size. A, B, brachial valves; C, pedicel valve. Concord, Kentucky, 
from lower part of Liberty member. 
Fig. 8. Plecta^nhonites plicatellus. A, a group of shells, some of them open but 
with the valves still attached. B, enlarged 5 diameters, with the brachial valve 
at top of figure. Copied from New York Paleontology, vol. Vlll, part 1, plate XV 
A, Figs. 34, 35. 
Fig. 9. Strophomena 7nillionensis . A, B, brachial valves; C, pedicel valve. 
An eighth of a mile west of the tunnel west of Million, Kentucky. Near the base 
of the Eden exposures in that part of Kentucky. 
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