Silurian Fossils 
67 
Pterinea nervata, sp. nov. 
{Plate IF, Fig. 60.) 
A third species of Pterinea found at Newsom, Tennessee, is in 
some respects intermediate between Pterinea hrisa and Pterinea 
newsomensis. Its left valve is marked by radiating striae, but these 
are less sharply defined than in Pterinea hrisa, and are much less 
numerous. The concentric lamellae show the fimbriate denticula- 
tions, but these are conspicuous only along the less elevated parts 
of the general body of the shell, where the shell is less worn. In 
general outline this species approaches Pterinea newsomensis, of 
which it may be regarded as a variety. However, in the case of 
Pterina nervata, when the shell is more or less worn, the general 
body of the left valve is seen to be covered by radiating striations 
of various size. The more prominent striae number about four 
in a width of 5 mm., the intermediate spaces being occupied by 3 
to*5 much finer striae, visible under a lens. The species is char- 
acterized by the more distant radiating striae, between which are 
a number of much finer striae. In size, this shell equals Pterinea 
newsomensis. 
Waldron bed: Newsom, Tennessee. 
Rhombopteria (Newsomella) ulrichi, sp. nov. 
{Plate IV, Figs. 62 d, B.) 
In surface ornamentation this shell is closely allied to Rhom- 
hopteria mira, described by Barrande from the Silurian lime- 
stone of Bohemia. In our shell, however, it is the right valve 
which is convex and which carries the characteristic ornamenta- 
tion. This consists of two systems of striations, m-ore or less radi- 
ating, crossing each other at an angle of about 30°. In addition 
to this there are strong lamellose concentric lines of growth, rather 
distant from each other, the free edges of these lamellae being some- 
times about a millimeter in width. In one shell, the distance from 
the beak to the posterior end of the hinge line is 21 mm. The out- 
line of the posterior lobe is slightly concave and makes an angle of 
about 45° with the hinge line. The height of the shell at the 
posterior extremity of the hinge line is almost 21 mm. The height 
where the sinuous outline of the anterior lobe begins is about 
13.5. The upper part of the outline of the anterior lobe makes 
an angle of about 60° with the hinge line. The crossing of the 
