



6 -A PRELIMINARY REPORT ON THE AQUATIC INVERTEBRATE FAUNA 

 OF THE YELLOWSTONE NATIONAL PARK, WYOMING, AND OF THE 

 FLATHEAD REGION OF MONTANA. 



BY s. A. FORBES, 



Professor of Zoology, University of Illinois, 



INTRODUCTORY. 



The immediate impulse to the investigation of the aquatic invertebrate fauna of 

 Wyoming and Montana, here reported in a preliminary way, was supplied by the 

 ichthyological work of Dr. David S. Jordan, in the Yellowstone National Park, in 

 1889, and of Prof. B. W. Evermann, in Montana and Wyoming, in 1891. 



The waters of Yellowstone Park had been reconnoitered by Dr. Jordan for the 

 special purpose of ascertaining precisely which of them were destitute of fish and 

 what was the cause of their barrenness. This having proved to be topographical in 

 every case some physical barrier to the entrance of fishes from below it seemed 

 possible to stock these waters permanently with valuable game-fishes, and thus greatly 

 to increase the attractiveness of the Park to a considerable class of travelers. Pre- 

 liminary to this, however, it was evidently desirable that a full knowledge should be 

 had of the variety and abundance of the lower animal life of these fishless waters, 

 since upon this the fishes introduced must chiefly depend for food. To this practical 

 end it was the wish of Hon. Marshall McDonald, United States Commissioner of 

 Fish and Fisheries, that my own investigations made in 1890 should be immediately 

 directed ; but with the understanding that the opportunity thus afforded for a general 

 zoological survey of the waters of Yellowstone Park should be improved to the best of 

 my ability. 



My associate in 1890 was Prof. Edwin Linton, of Washington and Jefferson College, 

 Pennsylvania, who, although specially charged with another duty, that of a study of 

 the parasites of fishes in these waters, rendered me constant and invaluable service in 

 my own special field. 



In 1891 it was niy general purpose to cooperate with Prof. Evermann in an 

 exploration of the waters of Montana and Wyoming, to be made with reference to 

 the location of a fish-hatchery; but in this, as in the preceding year, I made every 

 effort to become as thoroughly acquainted with the animal life of the waters which 

 I examined as the brief time spent in each locality would permit. 



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