PLATE 9 



Fig. 1. Basin at the head of Big Creek (Camp no. 4, 8000 feet alti- 

 tude — the ridges attain a height of 9000 feet), Pine Forest Mountains. 

 Humboldt County, Nevada; July 1, 1909. Artemisia tridentata is seen in 

 the foreground. The conifers are Finns flexilis, while the smaller trees 

 and most of the brush-like patches are Popnlus tremuloides. The animals 

 found here were for the most part Transition species, although the pres- 

 ence of Nucifraga Columbiana, Hylocichla ustulata sicainsoni, Zonotricliia 

 leucophrys leucophrys, and Sorex palustris navigator indicates an infusion 

 of Boreal elements. 



Fig. 2. Tract of country at the head of Big Creek (near Camp no. 4, 

 8000 feet altitude), Pine Forest Mountains, Humboldt C'ounty, Nevada; 

 July 29, 1909. The peculiar species of meadow mouse, Microtus (Lagurus) 

 intermedins, was found in the Artemisia tridentata shown in the fore- 

 ground, and was discovered nowhere else in the mountains. Immediately 

 back of the sagebrush a line of Populus tremuloides appears, and then a 

 few limber pines (Pinus flexilis). The brush-like vegetation in the back- 

 ground is dwarfed and gnarled Populus tremuloides. Nucifraga columbiana 

 and Colaptes cafer collaris were frequently heard in the pines, and Vermivora 

 celata orestera was noted in the aspens. 



4:^(11 



