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- 

 terested in the Salmonidae of the west, the trout, grayling and sal- 

 mon, and much money has been spent in investigating the subject 

 in this region. In i88g 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 of 

 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 ot 

 a few 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 a sort of 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- 



