JUL io 
STATE GEOLOGIST. 
APPENDIX D 
I: / 
CASTOROIDES OHIOENSIS, F^^er. 
BY N. H. WINCHELL. 
In the city of Minneapolis, while digging for a cistern on the corner of 
Washington avenue and Fifteenth avenue north, Mr. — Sommers discovered, 
at the depth of eight feet, the left mandibular ramus of this rare beaver- 
like rodent. The position is within the Valley of the Mississippi River, and 
under the sandy loam that lies on the brick clay. Referring to the diagram 
opposite page 168 of the report for 1876 (fifth report), its position is illus- 
trated. It lay near the bottom of the "sandy, loam-covered, gravelly plain," 
about twenty feet above the river, and over the brick cla}^ so near the 
brick clay that in excavating in search for other pieces, some of the clay was 
thrown out. Accompanying it were fragments of Unio shells. It hence 
belongs to that period of time when the Mississippi extended betAveen the 
high drift bluffs that enclose the city of Minneapolis, and which are about 
two miles apart, and hence to the flood, or "terrace," epoch, of the glacial 
period. Probably the ice of the glacial period still prevailed over the 
northern part of the State, its dissolution supplying the abundant water 
which kept the Mississippi at that stage. 
This rodent was first found in the State of Ohio, at Nashport, Licking 
•County, and was described anonymously, but not named, by J. W. Foster, 
in the American Journal of Science and Arts for 1837, with figures, and 
subsequently named by him in the 2d Report on the Geology of Ohio, in 
1838. It was again found at Clyde, Wayne Count}^, New York, and was 
described and figured by Wyman in the Proceedings of the Boston Society 
of Natural History, in 1846. This discovery embraced the right ramus and 
the entire skull. In the University Museum are perfect plaster casts of 
these specimens, the original of which are in the museum of Geneva College. 
The remains of the same animal (ramus of the lower jaw) have been found 
also at Memphis, Tenn., which were described by Wyman in the Am. 
Jour. Sci. and Arts for 1850, vol. X, and in the third volume of the Proc. 
Bos. Soc. (1850); also by Agassiz in Proc. Am. Assc. Adv. Sci. for 1851. 
Mr. J. Le Conte records its discovery at Shawneetown, Illinois, in the Proc. 
Phil. Acad. Nat. Sci., vol. VI , p. 53, and J. Leidy notes fragments of teeth 
from the Ashley River, South Carolina, and a skull near Charleston, Coles 
County, 111. Wyman also mentions its discovery near Natchez, Mississippi, 
and in Louisiana, and A. Winchell records it in Michigan, in the American 
Naturalist for 1870. J. A. Allen reports it from Dallas, Dallas County 
Texas, from the alluvial deposits of the Trinity River, associated with the 
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