72 
A ug. F. Foerste 
Scenidium bassleri, sp. nov. 
{Plate IV, Figs. 68 A, B.) 
Shell small, with four or five plications on each side of the 
median depression in the brachial valve, occasionally with two 
additional narrow plications on the sides of this depression ante- 
riorly, and sometimes with a narrow intercalated plication even 
in the space between the first and second conspicuous plications, 
counting from the depression outward. The median plication of 
the pedicel valve is distinctly elevated. From this the shell slopes 
convexly toward the margins of the shell. There are four or five 
lateral plications on each side, and also occasionally several narrow 
intercalated plications, near the median parts of the shell. The 
characteristic features of this species are the small number of 
plications and the presence of very distinct concentric striae, rather 
distant from each other, considering the size of the shell. Width, 
5.3 mm.; length, 4 mm.; depth, 2.2 mm. Named in honor of Adr. 
Ray S. Bassler. 
Waldron bed: Newsom, Tennessee. 
Rhipidomella lenticularis. 
{Plate II, Figs. 28 A, B.) 
Largest specimen 28 mm. long, 36 mm. wide. Valves moder- 
ately convex, the greatest convexity apparently posterior to the 
center of the shell. Form subcircular, striae about 160, about 12 
to 14 in a width of 5 mm. The hinge line has a length of about 
18 to 20 mm., the postero-lateral outline is rounded. Evidently 
related to Rhipidomella circulus^ but with more numerous and finer 
radiating striae. 
Brownsport bed: glade southwest of Brownsport Furnace, three 
miles west of Vice landing, Tennessee. 
Rhipidomella saffordi. 
{Plate I, Figs. 17 A, B, C.) 
A very small species; length, 8 mm.; width, 9 mm.; thickness, 
scarcely 4 mm. Brachial valve with a median depression which, 
considering the size of the species, is deep and broad. Pedicel 
valve evenly convex. Radiating striae about 6 in a width of 2 mm. 
Brownsport bed : in massive limestone near top of Brownsport 
