Silurian Fossils 83 
Width, 28 to 30 mm. This is evidently the species identified by 
Roemer with Orthothetes suhplanus. 
Brownsport bed: glade southwest of Dixon Spring, also ac 
Pegram, Tennessee. 
Plectambonites tennesseensis. 
{Plate I, Figs. 5 A, B, C, D, E.) 
Width, 7 to 9 mm.; convexity, 2.2 mm.; pedicel valve with 5 
more conspicuous radiating striae, distinct even near the beak, the 
intermediate spaces occupied in each case by a single radiating 
striation which extends only halfway from the margin of the shell 
toward the beak. Finer radiating striae practically obsolete. Can- 
centric markings of the shell rather distant, distinct, due to differ- 
ence in color caused by clay entering the thin spaces left at different 
stages of growth. 
Waldron bed: Iron City, at Cedar Bluff, also at the station; 
Swallow Bluff; along the river three-quarters of a mile above the 
landing at Clifton; along the road leading east from New Era; 
Newsom; all in Tennessee. 
Strophonella tenuistriata, sp. nov. 
{Plate II, Figs. 20 B, A.) 
Evidently related to Strophonella roemeri, but the shell is smaller, 
the outline is more semicircular, and the curvature of the shell 
where it is deflected anteriorly is much more moderate and not 
at all sufficient to be called geniculate. Width, 31 mm.; length, 
20 mm. Brachial valve distinctly concave over the larger part of 
the flattened area anterior to the beak, reversal of curvature begin- 
ning about 10 or ii mm. anterior to the beak. Pedicel valve dis- 
tinctly convex for a distance of about 8 mm. anterior to the beak, 
the remainder following the curvature of the brachial valve. Sur- 
face with fine radiating striae, 5 to 8 more prominent striae in a 
width of 5 mm., separated by 3 to 6 finer striae. Inner surface 
granulose. This is probably the species identified by Roemer 
with Strophonella euglypha. His specimens were fragmentary, 
his figures were restored, and the curvature of the shell as indicated 
by fig. 3c, plate 5, of his work, Stlurische Fauna des westlichen 
Tennessee, is probably incorrect at the anterior extremity; if the 
anterior part, 5 mm. long, were omitted, the figure would be a fair 
