24G The Ohio Journal of Science [Vol. XVII, No. 7, 



Stropheodonta (?) sp. Plate IX, Fig. 4. 



Valve convex anteriorh', the present flattening of the shell posteriorly- 

 assumed to have been due, in part at least, to pressure; assumed to be 

 a cast of the exterior of the pedicel valve. The original convexity 

 may have equalled 3 millimeters. Radiately striated with coarse and 

 fine striae. The coarser striae tend to be from three-quarters of a 

 millimeter to nearly a millimeter apart, additional striae being inter- 

 calated at about one-third of the length of the shell, and also at two- 

 thirds the length of the shell from the beak. Betw^een these coarser 



.^.h of the shell from 

 striae there are much finer striae, about four or five occurring between 

 each pair of coarser striae. Shell wrinkled concentrically in a peculiar 

 zigzag manner, excepting along the hinge-line where the wrinkles are 

 obliquely inclined in such a manner as to suggest an acute prolongation 

 of shell at the postero-lateral angle. The zigzag wrinkling suggests 

 the crossing of two sets of wrinkles at angles varying from 70 to 90 

 degrees on different parts of the valve. Since the specimen consists 

 of a natural cast of the exterior of the valve, no evidence regarding 

 its interior is offered. 



Found nine feet above the base of the Cedarville dolomite, 

 at the Lewisburg Stone Company quarry, located a mile north- 

 west of Euphemia, a village directly north of Lewisburg, Ohio. 

 This is the type locality for the Euphemia dolomite. Here 

 the following section is exposed, in descending order: 



Cedarville dolomite, lower part very porous 14 ft. 6 in. 



Springfield dolomite, dense, bedded 7 ft. 9 in. 



Euphemia dolomite, rock very porotis, and mottled or with whitish 



blotches 4 ft 6 in. 



Laurel limestone, whitish, resembling Dayton limestone 8 ft. 10 in. 



Osgood clay, middle part shaly, upper and lower part more 



indurated 4 ft. 



Dayton limestone, light blue, dense 8 ft. 



Brassfield limestone, estimated from drill-hole at 22 ft. 



Strophomenoid shells ornamented with zig-zag wrinkles, or 

 with two systems of wrinkles crossing at various angles, have 

 been known for many years. This type of ornamentation how- 

 ever, probably is not limited to a single genus. 



In 1848, Barrande described from the Silurian strata of 

 Bohemia, under the name Leptcena stephani (Brachiopoden der 

 Silurischen Schichten von Bohmen, Vol. 2, PL 20, Figs. 7 a-h) 

 a form which appears to be a Stropheodonta with an ornamenta- 

 tion similar to that of the Devonian species Stropheodonta 

 patersoni, Hall, but with a greatly elongated hinge-line and 

 with a remarkably strong curvature antero-posteriorly. 



