66 
Augr. F. Foersfe 
The conspicuous features of this shell compared with the species 
described from Waldron are as follows. The radiating and con- 
centric striae are more numerous, and without fimbriae. The ante- 
rior lobe is longer; its upper edge is more nearly parallel to the 
hinge margin; the sinuosity limiting it from the general body of 
the shell, originates farther from the beak. The posterior lobe is 
more extended along the hinge line. The anterior outline of the 
shell forms a much sharper angle with the hinge line, and the 
anterior height of the shell, in consequence, is less. 
Waldron bed: Newsom, Tennessee. 
Pterinea newsomensis, sp. nov. 
{Plate IV, Figs. 59 A, B.) 
Compared with Pterinea hrisa, from the Niagaran of Illinois, 
the species described as Pterinea brisa from the Waldron bed of 
Indiana differs considerably. The relative height of the shell is 
much greater; the anterior outline of the shell forms a smaller angle 
with the hinge line; the anterior lobe extends a shorter distance 
from the beak, both anteriorly and vertically; the posterior lobe 
is less extended along the hinge line and the sinuosity along its 
posterior margin is less. Both the radiating and concentric stria- 
tions are less numerous on the left valve, and the concentric striae 
or lamellae are more or less fimbriated where crossed by the radiat- 
ing striae, the so-called fimbriae consisting chiefly of short denticu- 
late projections, the margins of which are sharply turned upward. 
The shell attains a larger size than in the case of typical Pterinea 
brisa. The right valve is smaller, nearly flat, except toward the 
beak, where it is only slightly convex. Its surface is compara- 
tively smooth along the main body of the shell, being marked 
only by rather distant, low striae, which become indistinct toward 
the beak. The posterior lobe is marked by rather numerous sharp 
concentric striae, crossed by fairly distinct radiating striae. 
Height of one specimen, 26 mm.; length along the hinge line 
from the anterior edge of the anterior lobe to the tip of the posterior 
lobe, 29 mm. The sinuous outline limiting the anterior lobe begins 
6 mm. from the beak, and the extension of this lobe anterior to the 
general body of the shell is about 2.5 mm. Radiating striae about 
4.5 in a width of 5 mm. at a distance of 25 mm. from the beak. 
Waldron bed: Newsom, Tennessee. 
