AQUATIC INVERTEBRATE FAUNA OF WYOMING AND MONTANA. 
213 
From Yancey’s Ranch, which we reached on the 29th, we explored Slough Creek 
above the lower rapids, and some alkaline ponds near Barone tte’s Bridge, and on the 
31st went up the East Fork of the Yellowstone to Soda Butte Station on the creek of 
the same name. Collections were made on the way from Amethyst Creek, and from 
the East Fork of the Yellowstone, where this creek empties into it. September 1 we 
spent near Soda Butte Station, at work in the creek and in Trout Lake 2 miles 
north of the u station.” Returning to Yancey’s September 2, we examined the over- 
flow waters of the creek and searched the East Fork thoroughly at the Soda Butte 
bridge, and finished our collections from the river in that vicinity. 
On the 3d and 4th we continued to the canon and to the lake. The 5th was 
spent in making shore collections from Stevenson Island in Yellowstone Lake 
and in an examination of the small ponds and bayous of the island itself. On the 
forenoon of the 7th we finished our work on Yellowstone Lake by making three hauls 
of the dredge from the little steamer Zillah in the vicinity of Stevenson Island, at 
depths varying from 20 to 198 feet. 
The Avork of the season closed, September 10, with collections made from two 
localities previously examined by Prof. Evermann with reference to establishing a 
fish-hatchery — Bridger Creek and a cold spring adjacent, near Bozeman, and some 
springs and small streams near Boteler’s Ranch, just north of the Park. The return 
trip was made by the Northern Pacific Railroad, September 10 to 13. 
The collections of this summer were made under 73 collection numbers, represent- 
ing 23 localities. 
Apart from the practical points aimed at, and the opportunity to further extend 
our knowledge of the aquatic life of Yellowstone Park, a region whose zoology must 
long have an exceptional interest, I value the results of this year’s work chiefly as 
affording the means for a comparison of the animal life of two lakes so similar in 
many respects as Flathead and Yellowstone, and yet widely contrasted in altitude, in 
geological surroundings, and in topographical and geographical relations. It is, in my 
judgment, by a thorough examination and critical comparison of typical situations like 
these that the most interesting and immediately fruitful additions to zoological science 
are to be made in this field. I have only to wish that a longer stay on each of these 
lakes might have made possible a more minute and exhaustive study of their animal 
life and its relations to varying conditions of depth, bottom, temperature, season, 
weather, bionomic association, and the like. 
DISCUSSION OF THE COLLECTIONS. 
While the partial and, in most cases, merely preliminary way in which the mate- 
rial of these expeditions has as yet been studied makes any full discussion of the 
results impossible, it seems best that a report of progress should be made, presenting a 
summary review of the invertebrate life of these waters in the midsummer season, with 
descriptions or determinations of such new or particularly abundant and important 
kinds as have thus far been made out. Such a statement will include, in fact, the 
greater part of the economic results of immediate utility, and may be said, therefore, 
to fulfill the leading object of the work. This report may be most conveniently cast 
in geographical form, the life of each river system being separately discussed ; but, for 
want of time to examine the entire mass of the collections, only a preliminary account 
of the fauna of the still waters visited, from temporary pools to Flathead and Yellow- 
stone lakes, will be given at present. 
