April, 1917] Silurian Fossils from Ohio 193 



Corporation quarry, immediately south of the Marshall pike, 

 in the eastern part of the town. At this quarry, the Pentamerus 

 bearing dolomite, correlated with the Cedarville dolomite of 

 the more northern sections in southwestern Ohio, is underlaid 

 by two feet of clay shale, and next by fourteen feet of a bluish, 

 apparently argillaceous limestone, rather massively bedded. 

 Fossils are abundant in the clay shale, much less abundant in 

 the upper part of the massive limestone, and comparatively 

 scarce in the middle and lower parts of this limestone. Holo- 

 phragma calceoloides also is common in the two-foot clay shale, 

 and occurs in moderate numbers in the upper half of the 

 underlying massive limestone. 



At the Trimble, Beech, or Railroad quarry, a third of a mile 

 north of the Zink quarry, the Pentamerus bearing dolomite, 

 correlated with the Cedarville dolomite, is underlaid by clay 

 shale, three feet three inches thick. Below this occurs the full 

 section of the blue massive-bedded limestone seen in the lower 

 part of the Zink quarry. Here its total thickness is 21 feet, 

 and it is underlaid by well-bedded, laminated, cherty limestone 

 in which fossils are few. Holophragma calceoloides occurs here 

 both in the clay shale and in the upper half of the underlying 

 massive limestone, but in much smaller numbers than at the 

 Zink quarry. 



Holophragma calceoloides occurs also at two localities along 

 the Danville pike, west of Hillsboro. The first locality is a 

 quarry south of the pike, about a quarter of a mile west of the 

 town. Here it occurs in the upper part of the massive blue 

 limestone. The clay shale is absent, and the overlying dolomite 

 does not contain Pentamerus. The second locality is a quarry 

 north of the pike, and about an eighth of a mile farther west 

 than the first quarry. Here Pentamerus is common at the top 

 of the quarry. Below the Pentamerus bearing horizon is a 

 section ten feet thick in which the dolomite contains no 

 Pentamerus. Below this ten-foot section occurs the massive 

 blue limestone, containing Holophragma calceoloides in its upper 

 half. At neither of these two localities is the Holophragma 

 common. At the first locality, south of the Danville pike, the 

 shaly, thin-bedded, cherty rock, seen at the base of the Trimble 

 quarry, is exposed. 



The two-foot clay shale layer, and the 21 -foot massive blue 

 limestone section at the Trimble, Beech or Railroad quarry, 



