251 



Occurrence. MARTINSBURG SHALE (Sinuites bed). Pennsylvania. 

 The type specimens are from one mile- south of St. Thomas. 



Collections. Maryland Geological Survey, IT. S. National Museum. 



STROPHOMENA HALLIE (S. A. Miller) 

 Plate LIV, Figs. 7-9 



Streptorhynchus ? hallie Miller, 1874, Cincinnati Quart. Jour. Sci., vol. i, 



p. 148, figs. 14-16. 

 Strophomena hallie Foerste, 1914, Bull. Sci. Lab. Denison Univ., vol. xvii, 



p. 38, pi. ii, figs. la-e. 



Description. " Shell sub-trigonal in outline, concavo-convex, deflected 

 laterally, resupinate, rather thin and frail; hinge scarcely equalling the 

 greatest breadth of the valves; length and breadth about three-fourths 

 of an inch. 



" Dorsal valve convex in the central part, flattened on the umbone and 

 deflected laterally ; surface marked by moderately coarse, radiating striae, 

 which increase by intercalation of smaller ones ; area linear, beak not 

 distinct from the edge of the area. Interior showing cardinal process to 

 be very small and divided into two teeth-like parts, directed a little 

 forward and flattened on their faces; socket-ridges small, short, and 

 oblique; mesial ridge scarcely perceptible without a magnifier, radiating 

 striae plainly visible. 



" Ventral valve moderately concave in the central and anterior regions, 

 but slightly convex at the beak, which is perforated and projects slightly 

 beyond the edge of the area; surface marked by radiating striae, which 

 increase by even bifurcations ; area narrow and sloping laterally ; foramen 

 closed by a rounded deltidium for the reception of the cardinal teeth of 

 the dorsal valve. Interior showing trigonal hinge and circular cavity; 

 marked by radiating striae." Miller, 1874. 



Occurrence. MARTINSBUBG SHALE (Eden division). Jordans Knob 

 one and one-half miles northeast of Fort Loudon, and Tuscarora Moun- 

 tain, two and one-half miles southeast of McConnellsburg, Pennsylvania. 

 Eden shale at Cincinnati, Ohio. 



Collection. U. S. National Museum. 



