44^ The Ohio Naturalist. [Vol. XII, No. 3, 



Franklin county, although this is the only one of the fossils charac- 

 teristic of the basal part of the upper or Orcgonia division of the 

 Arnheini which has a fairly general geographic distribution in the 

 area designated. In most of this territory, the Arnheim consists 

 of argillaceous limestone, and indurated clay layers interbedded 

 with much larger quantities of soft clay. The lower Arnheim 

 does not differ lithologically from the upper part. 



The chief characteristic of the Arnheim in Franklin and Union 

 counties, in Indiana, is the presence of a variety of Dahnanclla 

 jugosa in rather large numbers. Northwest of the home of William 

 Bauman, two miles southwest of Brookville, DalmaneUa has a 

 considerable vertical range above the Dinorthis carlcyl horizon. 

 At New Trenton, Indiana, Dahnauclla has a considerable vertical 

 range below the Dinorthis carle yi layer; in fact, it occurs even as 

 low as the Mount Auburn. North of Brookville, as far as the 

 northern boundary of Franklin county, DalmaneUa ranges from 

 several feet above the DinortJiis carleyi horizon to at least 10 

 feet below that level. 



6. Ohio. 



DalmaneUa has a considerable vertical range in the Arnheim 

 also in the western half of Hamilton and Butler counties, in Ohio. 

 Farther eastward, as far as Adams county, on the Ohio river, 

 DalmaneUa is restricted, in the Arnheim, to a vertical range of only 

 a few inches, at or immediately above the Plaiystrophia ponderosa 

 horizon, and distinctly beneath the Leptaena richmondensis and 

 Dinorthis carleyi horizons. Wherever, at these more eastern 

 localities, DalmaneUa has a considerable vertical range, it is known 

 to characterize the Waynesville member. The result is that, 

 fsirther eastward, DalmaneUa may be used to identify readily the 

 Waynesville member, especially the lower part, where other con- 

 spicuous characteristic fossils are not common, while in the western 

 part of Butler and Hamilton counties, and in Franklin county, 

 this species may prove misleading if only a superficial study be 

 given to a line of outcrops. 



A most peculiar section, differing in some respects from any 



other known, occurs about a mile north of Collinsville, or eight 



miles northwest of Hamilton, Ohio. The top of the Arnheim 



is not exposed. 



Nodular argillaceous limestone near the top of the Arnheim... 2ft. 



Interval with Byssonychia and Rafinesquina common 11 ft. 6 in. 



Clay with DalmaneUa and with a single loose specimen of 



Dinorthis carleyi which may have come from this horizon. . 3 ft. 6 in. 



Clay and limestone. Topmost layer wave-marked 7 ft. 4 in. 



DalmaneUa abundant in clay and thin limestone 6 ft. 8 in. 



'Clay interbedded with limestone G ft. 9 in. 



Argillaceous rubble limestone 2 ft. 9 in. 



Highest Leptaena richmondensis horizon. 



Interval with Plaiystrophia ponderosa at various levels 1 ft. 9 in. 



Leptaena richmondensis. 



Interval 1 ft. 8 in. 



Flalyslrophia ponderosa just above creek level. 



