April, 1017] Silurian Fossils from Ohio 195 



Corporation quarry, in the eastern part of Hillsboro, Ohio. It 

 occurs at the same horizon, but in smaller numbers, at the 

 Trimble or Railroad quarry, a third of a mile north of the Zink 

 quarry. Specimens occur also in the upper part of the massive 

 blue limestone exposed in the quarry a quarter of a mile west 

 of Hillsboro, on the Danville pike. 



Specimens not to be distinguished from t^^pical Zaphrentis 

 digoniata, from the Lilley member of the West Union formation, 

 at Hillsboro, occur in the upper third of the quarry at Cedarville, 

 Ohio, where only the Cedarville dolomite is exposed. Since the 

 upper limits of the Cedarville dolomite can not be determined 

 in the area surrounding Cedarville, nothing more definite 

 regarding the stratigraphic position of these Cedarville spec- 

 imens can be stated at present. The specimens occur chiefly as 

 casts of the calices, but impressions of the exterior of the entire 

 corallum also occur. 



In Streptelasma angiilatiim, Billings, from the English Head 

 and Charleton formations, in the Richmond of Anticosti, and 

 in some of the younger specimens of Streptelasma robustum, 

 Whiteaves, from the Richmond of the Red River Valley, in 

 Manitoba, the corallum is more or less strongly angulate along 

 the convex curvature of the corallum. In both species, the 

 anterior outline is distinctly concave, and the posterior or 

 cardinal outline is strongly convex, when the corallum is viewed 

 from the side. 



Since no attempt ever has been made to locate the exact 

 horizon of the rich fauna in the quarry at Cedarville, Ohio, in 

 that part of the Silurian section usually referred to the Cedar- 

 ville dolomite, the following notes may be of service. At the 

 quarry immediately north of the railroad and about a third of a 

 mile west of the railroad depot, the top of the exposed rock is 

 about two feet above the level of the railroad track. The 

 section here is as follows, given in descending order: 



Cedarville dolomite, richly fossiliferous 12 ft. 



Amphicoelia costata horizon 

 Cedarville dolomite, fossils common 7 ft. 



Horizon 1003 feet above sea level. 

 Cedarville dclomjite, massive, breaking up into irregular lavcrs; fossils 



few ■ 3 ft. 



Cedarville dolomite, massive, crinoidal, fossils few 7 ft., 6 in. 



Cedarville rock, not exposed, covered by water collecting at bottom 



of quarry ; fossils few 11 ft. 



