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THE MOLLUSCAN FAUNA OF THE GENESEE 
RIVER. 
FRANK COLLINS BAKER. 
Tue study of faunal distribution has always been a favorite 
occupation of zoólogists, and particularly of those interested in 
the study of the Mollusca, as in this branch we find a very 
large number of species, covering wide areas and subject to 
every variation of environment. In no department of the Mol- 
lusca is this of such absorbing interest as in the fresh-water 
forms (unless we except, perhaps, the air-breathing pulmonates), 
especially those inhabiting a large river wherethere are several 
barriers to the homogeneous distribution of its shell fauna. 
During the past summer the writer spent several months in 
Such a study of the Genesee River, where the environments 
are quite different in several parts of the stream, with a corre- 
sponding difference in the mollusk fauna. The river was care- 
fully surveyed from near its mouth on Lake Ontario to beyond 
South Park, a distance of ten miles. A large collection was 
made, which is now in the museum of the Chicago Academy 
of Sciences. My thanks are due to Miss Edna E. Hall for 
valuable assistance in collecting, and to Rev. John Walton 
for many notes, 
The Genesee River rises in Potter County, Pennsylvania, 
and flows in a generally northward direction for about 120 
miles, emptying into Lake Ontario, seven miles north of 
Rochester, N. Y. The Genesee valley is very fertile, and the 
river flows between low banks rich in vegetation. Before 
passing Rochester the river is deep, the banks muddy, and the 
current steady but not very swift. From a point a little north 
of Genesee Valley Park (or South Park) the bottom of the river 
“comes very rocky, the current swift, and at Rochester the 
"VT drops to the valley below in three series of falls of 
considerable magnitude. 
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