276 Proceedings of Societies. [ ZOE 
Despite the perpetual explorations of the Yellowstone Park by 
tourists, there is still much to be learned there from a zoological 
standpoint. Fish Commissioner McDonald has been especially in-s 
terested in the Salmonidz of the west, the trout, grayling and sal? 
mon, and much money has been spent in investigating the subject 
in this region. In 1889 Messrs. Jordan and Gilbert made a careful 
survey of the park for the purpose of determining the limits of the 
troutless area, which is situated in the Shoshone and Lewis Lake 
region, and includes the streams running from these two bodies ot 
water. The explanation of this troutless area is not far to seek. 
The district in question is a greatly elevated volcanic region form- 
ing a high plateau, and the streams arising upon it invariably plunge 
down high falls. Accordingly, although trout are plentiful up to 
the falls they are unable to ascend to the plateau above. This 
elevated area is a beautifully timbered region, interspersed with 
grassy meadows affording ample feed for horses, and has now been 
well stocked with trout by the Fish Commission. 
In 1891 I was sent with Prof. Evermann, of the Fish Commission, 
to this locality to see how the trout which had been left there were 
doing, and to see what other streams in the region might be stocked 
to advantage. A fine opportunity was also presented to work out 
an interesting problem in the geographical distribution of the trout 
of this district. We started from Two Ocean Hotel, with a pack 
train of eighteen horses and complete outfit, for Two Ocean Pass, a 
pretty meadow valley of high elevation, from which flow a number. 
of streams, some ultimately reaching the Atlantic and some the 
Pacific system of water courses. The trout in the two water-courses 
had been considered as two species, but Dr. Jordan, after an ex- 
amination of a large series, pronounced them to be the same. An 
examination showed that one Atlantic stream had piled up a gravelly 
bank and the water had been dammed up so that by the removal of 
afew stones a strong stream ran off towards the Pacific creek. © 
Trout were found on both sides of the divide in this instance. Near 
at hand another stream was found, which could be made to flow in 
both directions from the divide by diverting its channel at a slight 
bend, and allowing the water to flow up one arm and down the 
other of asortof Y. 
The bull-head, blob, or miller’s thumb, as it is variously called, 
_is found in this troutless area above the falls, especially in the Gib- 
