May, 1919] Silurian Fossils From Ohio 379 



lobes of the cardinal process, two additional very low callosities con- 

 verge toward the front so as to meet within four millimeters from the 

 hinge line. Two low diagonal lines separate the posterior part of the 

 muscular area from the anterior parts, and a low median line often may 

 be noted in the intemiediate area. In both valves, the interiors are 

 finely granulated. The granules of the brachial valve appear somewhat 

 coarser, especially posteriorly, on each side of the muscular area. In 

 both valves the granules tend to be arranged along the crests of the lines 

 which evidently correspond to the grooves between the striae appearing 

 on the exterior of the shells. 



No interiors of typical Br achy prion newsomensis, from the 

 Waldron of Tennessee, are at hand for direct comparison. 

 The exteriors appear similar. (Bull. Sci. Lab. Denison Univ., 

 14, 1909, p. 87, pi. 4, fig. 67.) 



Camarotoechia indianensis (Hall). 

 Plate XVII, Figs. 4 A-C. 

 1863. Rhynchonella indianensis Hall, Trans. Albany Inst., vol. 4. p. 215. 



This familiar Waldron species is characterized by the presence of a 

 low fold supporting four plications, and a shallow sinus containing three 

 plications. All of the plications tend to be low and rounded, but are 

 distinct as far as the beak. The general form is rhomboid-ovate. At 

 the anterior margin of the shell the slope of the sinus meets that of the 

 fold at a right angle, producing an oblong outline on lateral view. 



Shells having the same general characteristics occur in the 

 Holophragma zone at the top of the upper or Lilley member of 

 the West Union formation, at the Zink or Corporation 

 quarry, within the eastern limits of Hillsboro, Ohio. 



Camarotoechia cf. neglecta (Hall). 

 Plate XVII, Figs. 5 A-C. 



The type of Camarotoechia neglecta is a Clinton form, from 

 the Reynale's limestone of New York. With this Clinton form 

 it is customary to identify certain Niagran forms which may 

 eventually prove to belong to a distinct species. 



The Niagaran forms differ from Camarotoechia indianensis in their 

 smaller size, higher fold and deeper sinus, distinctly more angular 

 plications, and a somewhat more triangular form. Frequently the 

 depressed area within the sinus meets the area on the fold of the opposite 

 valve at an angle which is more acute than a right angle. 



At the Holophragma zone, in the eastern part of Hillsboro, 

 Ohio, occasional specimens of Camarotoechia are found which 

 resemble Camarotoechia neglecta in their more angular plication, 



