72 
Aug. F. Foerste 
neglecta, and occasionally Strophomena nutans is seen earlier than 
Strophomena neglecta, so that the order of succession becomes 
Strophomena nutans, Strophomena neglecta, Strophomena vetusta- 
precursor, with the range of Strophomena neglecta overlapping 
that of the two other species. 
At Moores Hill, Indiana, and at Oxford and Oregonia, Ohio, 
the total thickness of this Strophomena section, at the middle of 
the Blanchester division, including the three species named, 
equals about 12 feet. At Jacksonsburg and Clarksville, Ohio, 
it equals 8 feet. At Canaan, in the northern part of Jefferson 
county, Indiana, in Adams county, Ohio, and at Concord, 
Kentucky, it equals only 3 or 4 feet. At Moores Hill, and Weis- 
burg, Indiana, and at Oregonia and Clarksville, Ohio, the top 
of this Strophomena section extends to within 5 or 6 feet from the 
base of the upper Hehertella insculpta zone, which forms the 
base of the Liberty bed. Where the Strophomena section is 
limited to only several feet, its distance from the upper Heher- 
tella insculpta horizon may equal 10 to 15 feet. 
The greatest vertical range of Strophomena nutans usually does 
not exceed 2 or 3 feet, but occasionally equals 7 feet. 
The geographical range of Strophomena nutans extends from 
the southwestern part of Adams county, 2 miles northeast of 
Brady ville; northward as far as the Narrows, east of the Pin- 
nacles, 4 miles southwest of Dayton, Ohio ; westward to the north- 
ern edge of Union county, a mile and a half south of Abingdon, 
Indiana, and southward to Moores Hill, also in Indiana. 
Fig. 2 B, on plate III of this Bulletin, presents a view of a speci- 
men of Strophomena, somewhat resembling Strophomena nutans, 
from the Whitewater beds at Tate Hill, east of the Focke slaugh- 
ter house, on the Springfield pike, in the eastern part of Dayton, 
Ohio. The thickened anterior border ascends vertically a dis- 
tance of 7 mm. The presence of a similar outline and of a simi- 
lar considerable thickening of the interior border of the pedicel 
valve may not be indicative of any direct relationship of this 
shell to Strophomena nutans. Similar conditions may give rise 
to similar forms at different times without predicating a similar 
line of descent. 
A fragment of Strophomena, resembling Strophomena nutans, 
was found 3 miles north of Wekwemikongsing, on the eastern 
shore of Manitoulin Island (plate XI, Fig. 8). 
