Silurian Fossils 
8i 
Chonostrophia lindenensis, sp. nov. 
{Plate III, Fig. 52) 
Shell with extremely fine, filiform radiating striae, visible under 
, a lens. Pedicel valve slightly convex near the beak and slightly 
width of the shell, compared with its length, will distinguish it 
readily from any species described hitherto. 
Linden bed: Pyburn bluff, Tennessee. 
Triplecia (Cliftonia) striata, sp. nov. 
{Plate III, Figs. 42 A, B.) 
The external aspect of this species is that of a small A try pa, 
but the internal structure indicates close relationship to Triplecia. 
Brachial valve circular in outline; pedicel valve more nearly 
ovate. Brachial valve strongly convex, raised so as to form a low 
broad median fold anterior to the middle. The shell starts at the 
beak with a median groove which is rather conspicuous along the 
posterior third of the shell. Pedicel valve rather strongly convex 
posteriorly, but bent downward anteriorly so as to form a broad 
shallow median depression, not always symmetrical. Radiating 
striae rather coarse and distant considering the size of the shell, 
about 7 to 9 in a width of 5 mm. Concentric striae probably were 
distinct on the original shells. Length of the pedicel valve, 13 mm. ; 
width, 13 mm.; depth, almost 3 mm. Length of brachial valve 
practically the same as that of the pedicel valve, but the depth is 
almost 6.5 mm. 
Interior of brachial valve with a linguliform cardinal process, 
1.7 mm. in length, and f mm. in width at the hinge line. This 
process becomes broader anteriorly, and divides near the tip into 
two short, sharply pointed, divisions. The impressions of two 
short sharply pointed crurse are seen in one of the specimens. 
There is a narrow median striation along the posterior third of the 
interior, corresponding to the median groove on the exterior. The 
interior cast of the pedicel valve indicates the presence of a rather 
high flat hinge area, whose length is about 8 mm. in a shell 13 mm. 
wide. The height of this area is estimated at almost 2 mm. A 
conspicuous cavity extended from the interior of the shell along 
the part enclosed within the beak, and opened by means of a small 
aperture at the tip of the beak. Teeth supported by short dental 
