Silurian Fossils 
97 
The teeth of the pedicel valve are supported by vertical dental 
lamellae, enclosing a cavity of ovate form, distinctly outlined in 
natural casts of the shell. None of the casts shows a distinct mus- 
cular area, but in an indistinct manner this area is represented by 
the indistinctness of the median plication of the cast, extending 
to a point 3.7 mm. from the beak. In the cast of this muscular 
area there is a slight and narrow median depression, and another 
is shown laterally, suggesting the muscular area of Rhynchotreta. 
Clinton bed: Clifton, Tennessee. 
Compared with Rhynchonella bidens, tht angulation produced by 
the fold and sinus along the anterior margin of the valves is much 
less, and the pedicel valve is less convex. The sinus and fold are 
relatively broader, and the lateral plications usually number three 
rather large ones, and one much smaller, the latter sometimes 
indistinct. It evidently is closely related to Rhynchonella whitii, 
from which it differs chiefly in the smaller size, and the less promi- 
nent fold and sinus. 
Rhynchonella (Stegerhynchus) neglecta-cliftonensis, var. nov. 
{Plate III, Figs. 48, A, B, C.) 
This shell is unquestionably congeneric with Rhynchotreta 
whitii-pr recurs or. The brachial valve possesses the same crural 
plates terminating anteriorl)/ at their inner angles with crural 
points. These crural plates rest upon the thickened shell beneath 
but are separated from each other by a space within which the thin 
longitudinal cardinal process may be seen distinctly. The teeth of 
the pedicel valve are supported by dental lamellae, and anterior to 
the space thus enclosed may be seen the faint traces of the muscu- 
lar area. The latter is indicated chiefly by the diminished distinct- 
ness of the plications which correspond to grooves between the 
plications of the exterior of the shell. 
There are four plications on the median fold, with 3 distinct and 
I indistinct plication on each side, on the brachial valve. In the 
sinus of the pedicel valve, there are three plications, with 4 distinct 
and I nearly obsolete plications on each side. 
Compared with Rhynchonella neglecta, from the Clinton group 
of New York, theshellislarger,broader, less triangular, flatter along 
the middle parts of the pedicel valve, and the number of lateral 
plications is smaller. 
Clinton bed: Clifton, Tennessee. 
