W.B. Davis 1935, Castle Creek, 8 mi., S Oreana, Owyhee Co. Idaho, May 27. There is a strip of Lower Sonoran zone along the Snake River which extends for some distance up the small creeks emptying into it from the south. This zone appears to be characterized by Greasewood as the dominant shrub, and in some cases associated with Rabbitbrush. The characteristic bird is the Western or Eastern Sagebird, particularly the former. All the higher country is dominated by Artemisia and is in, I should judge, Upper Sonoran zone. So far we have worked in no truly Transition zone, save perhaps the bottom of the canyon at Sabnow Creek west of Rogerson. At Oreana Mr. Bachman told me there were no ground squirrels of any sort in the valley -- that is, in the Lower Sonoran Life Zone, -- but that they were supposed to be quite common farther up in the foothills. He said, however, that there were Ammospermophilos, and coming over to the ranch today one was seen along the road. This is my first sight record this year, and last year