Maryland Geological Survey 111 



Genus PHOLIDOSTROPHIA Hall and Clarke 



Pholidostrophla. I'EXnsylvanica Kindle 

 Plate X, Figs. 8, 9 



Pholidost)-op?iia pennsylvanicus Kindle, 1912, Bull. U. S. Geol. Surv., No. 508, 

 p. 74, pi. V, figs. 1, 2. 



Description. — Shell small, concaAO-convex or plano-convex. Ventral 

 valve depressed convex, greatest width at hinge-line and salient cardinal 

 angles. Surface without radiating striae but with some indications ol 

 laniellose lines of growth. The impression of a single dorsal valve sup- 

 posed to belong to this species is slightly concave and shows a very short 

 slender septum extending 1 mm. from the hinge-line. The collection 

 contains six or seven specimens. An average specimen has a M'idth of 

 8 mm. at the hinge-line and a length of 6 mm. 



This shell resembles both P. iowensis (Hall) and Stropheodonta punti 

 Clarke in its smooth exterior. It is smaller than either of these however, 

 and does not possess the crescent-shaped ridges which characterize the 

 dorsal valve of P. iowensis. The absence of these may leave some doubt 

 as to the propriety of referring this shell to Pholidostrophia but the 

 smooth surface and the general features of the shell strongly indicate its 

 relationship to this group of the Stropheodontas. 



Occurrence. — Romney Formation, Onondaga Member. Williams 

 Road, 314 miles southeast of Cumberland. 



Collection. — U. S. National Museum. 



[E. M. Kindle.J 



Genus LEPTAENA Dalman 

 Leptaena rhomboidalis (Wilckens) 



Plate X, Figs. 10, 11 



Conchites rhomboidalis Wilckens, 1769, Nachricht von seltenen. Versteiner- 



ungen, p. 77, pi. vlii, figs. 43, 44. 

 Strophomena unduJosa Conrad, 1841, Fifth An. Rep. Geol. Surv. N. Y., p. 54. 

 StropJwmena dcpressa Vanuxem, 1842, Geol. N. Y., pt. iii, p. 79, fig. 5. 

 Btrophomena undulatus Vauuxem, 1842, Geol. N. Y., pt. iii, p. 139, fig. 3. 

 Leptaena tenuistriaia Hall, 1847, Pal. N. Y., vol. i, p. 108, pi. xxxi A, fig. 4. 



