140 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
spring and geyser formation, with numerous streams of hot water emptying int@ 
the lake, and large springs of hot water opening in the floor of the lake near shore. 
Trout abound in the vicinity of these warm waters, presumably on account of the 
abundance of food there. They do not love the warm water, but carefully avoid it. 
Several persons with whom I talked on the subject while in the park assert that 
diseased fish—that is to say, those which are thin and affected with fleshworms—are 
more commonly found near the warm water; that they take the bait readily, but are 
lazy. I frequently saw pelicans swimming near shore in the vicinity of the warm 
springs on the west arm of the lake. It would appear that the badly infested or 
diseased fish, being less active and gamy than the healthy fish, would be more easily 
taken by their natural enemies, who would learn to look for them in places where 
they most abound. But any cireumstances which cause the pelican and trout to 
oceupy the same neighborhood will multiply the chances of the parasites developing 
in both the intermediate and final host. The causes that make for the abundance 
of the trout parasite conspire to increase the number of adults. The two hosts 
react on each other, and the parasite profits by the reaction. 
An effective remedy might be found in the extermination of the peli- 
cans, providing they are the only final hosts of this parasitic worm, 
The relief which might thereby be afforded, however, is not of sufficient 
importance to justify the destruction of so interesting a feature of the 
park. The trout in that region is not important as a food supply; the 
diseased fishes are in most convenient places for capture, and with the 
increase in fishing will be drawn upon more largely than the healthy 
ones. The introduction of other species into the lake would, more- 
over, tend to improve conditions by adding new varieties of food for 
the trout, thereby probably diverting them more or less from the warm 
waters and imparting to them a more vigorous constitution. The peli- 
cans would also profit by this new source of food, the trout would 
suffer less from their attacks, and parasitism would be decreased in 
proportion. 
Other fish parasites were obtained in the Yellowstone Park by Prof. 
Linton, who has presented three reports treating of these interesting 
forms.* 
COLORADO AND UTAH. 
Investigations were conducted in Colorado and Utah during July 
and August, 1889, by Dr. David 8S. Jordan, assisted by Prof. B. W. 
Evermann, Mr. Bert Fesler, and Mr. Bradley M. Davis. The special 
object of this inquiry was to determine the character of the streams 
and lakes of the Rocky Mountains and the Great Basin as represented 
in this State and Territory, the variety and distribution of the food- 
fishes now inhabiting these waters, and their suitability for the intro- 
*On two species of larval Dibothria from the Yellowstone National Park. Bull. 
U.S. Fish Comm., 1x, for 1889, pp. 65-79, pls. XX V-xXXVII. 
A contribution to the life-history of Dibothrium cordiceps, a parasite infesting 
the trout of Yellowstone Lake. Idem, pp. 337-358, pls. Cx viI-CXIXx. 
On fish entozoa from the Yellowstone National Park. (Appendix 5 to this vol- 
‘ume. ) ? 
