418 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.56. 



width across the middle. The lateral slopes of the pedicle valve are 

 flatly concave, those of the brachial valve flatly convex. There are 

 generally six sharp plications on the lateral slopes which are broadly 

 spaced and iiave a slight tendency to curve, as do the lateral plica- 

 tions of Plaiystrophia paucijjlicata. The beak is prominent. 



Measurements. — 15.1 mm. along the hinge line, 14.1 mm. wide 

 across the middle, 10.5 mm. high, 7 mm. thick, 6.5 mm. sinal width. 

 4.8 mm. sinal depth, 2 mm. fold depth. 



Occurrence. — Maysville group: Base of the Fairmount beds at 

 Newport, Kentuck5^ 



Coty pes. —Cat. No. 48613, U.S.N.M. 



PLATYSTROPHIA NlXmA, new species. 



Plate 43, ligs. 42, 43. 



The specimens representing this species are small, with spreading 

 folds which scarcely rise above the convexity of the brachial valve; 

 and with broad shallow sinuses which have bent but slightly below 

 the inner edges of the lateral slopes of the pedicle valve. There are 

 six and seven fine, closely spaced plications on the lateral slopes. 

 The slopes of the brachial valves are flatly convex, while those of the 

 pedicle valve are flatly concave. The beaks of the pedicle valves are 

 prominent. The cardinal areas narrow rapidly and usually disappear 

 before the cardinal extremes are reached. The hinge-line is some- 

 what less than the width across the middle. 



Measurements.— % mm. along the iiinge line. 8.5 mm. wide across 

 the middle, 6.2 mm. high, 3.6 mm. thick, 3.5 mm. sinal width, 1.5 

 mm. smal depth, .5 mm. fold depth. 



Occurrence. — Maysville group: Base of Fairmount beds at Cin- 

 cinnati, Ohio. 



Coty'pes.—-C^i. No. 65945, U.vS.N.M. 



PLATYSTKOPKIA MORROWENSIS (James). 

 Plate 43, figs. 30-35, 50. 



Orthis (?) riwrroufiisis ,iAM)s,s, Cinciunati Quart. Journ. Sci., vol. 1, 1874, p. 21. 

 Platystrophia morrovem^is Foerpte, Bull. Sci. Lab. Denison Univ., vol. 16, 1910, 

 p. (iO, pi. G, figs. ll«-i". 



Mr. James has applied tiiis name to certain specimens which were 

 collected from the Cincinnati group of Warren County, Ohio. It is 

 a transversely globose species with sub-equally convex valves. The 

 hinge line varies from one-third to three-fourths the Avidth; the 

 cardinal areas are narrow and the cardinal angles round. The fold is 

 low and spreading; it rises very little above the general convexity of 

 the brachial valve. The sinus is broad and shallow in the middle 

 portion but becomes relatively deep at the front. Both the fold and 

 sinus are almost wanting at the beak. 



