JUMPING MOUSE 151 



in a depression in the ground and surrounded and overtopped by dead and 

 new grasses. There was a short curved outlet run at one side about one 

 inch (25 mm.) wide and 514 inches (130 mm.) long which led directly into 

 the grass and then disappeared. The nest proper consisted externally of 

 long flexible blades of grass of the previous year's growth; these were 

 arranged concentrically around the outside. Within was a soft lining 

 which consisted of finely shredded, last-year's grass blades together with 

 a few green ones. It was all perfectly dry though the surrounding meadow 

 was, as usual at this season, quite damp. This nest may have been merely 

 ' living quarters ' for an adult, and not intended for the reception of young. 



A local colony of Allen Jumping Mice was found on the floor of 

 Yosemite Valley near the foot of Yosemite Falls. To our own senses the 

 air is notably cold in that particular part of the Valley. A cold breeze 

 comes down from the falls much of the time, and the ice-cold water drop- 

 ping directly from snow fields 3000 feet above until well along in summer 

 also affects the temperature of the place. There is, in addition, a thick 

 canopy of shade from the enclosing dense stand of yellow pines, incense 

 cedars, white firs, and black oaks. In this 'boreal' spot jumping mice, 

 characteristic of the Canadian and Hudsonian zones above the Valley rim, 

 were present in numbers during June of 1915. The ground was covered 

 with a mat of dead pine needles and deciduous leaves, and there were 

 scattered plants of thimble berry, azalea, creek dogwood, and fern. Possibly 

 colonies of this rodent occur elsewhere in similar, cool situations on the 

 Valley floor, but we found no others. 



No data were obtained as to breeding, save that indications pointed to 

 the summer months as the breeding period. Elsewhere it has been found 

 that the Allen Jumping Mouse has rather large litters, 6 perhaps being an 

 average. Immature individuals about two-thirds grown were captured at 

 Merced Lake August 25 to 29, 1915, and near Williams Butte September 15, 

 the same year. 



Yellow-haired Porcupine. Erethizon epixanthum epixanthum (Brandt) 



Field characters. — Size larger than that of Sierra Marmot; tail less than half head 

 and body; pelage very long; upper surface and sides of body and tail with many barb- 

 pointed yellow quills which can be raised at will. Head and body 2iy2 to 27 inches 

 (545-682 mm.), tail 7 to 9 inches (175-225 mm.), hind foot 3% to 4% inches (95-120 

 mm.), ear about 1 inch (27 mm.) ; weight 15 to 20 pounds (estimated). [Measurements 

 from California specimens taken outside Yosemite region.] Body coloration blackish, a 

 few long hairs and the quills yellow except for black tips. Worlings: Areas on coniferous 

 trees denuded of bark and showing paired marks of incisor teeth, each mark about Vi inch 

 (6 mm.) broad (pi. 37a). Droppings: Pound on ground beneath 'barked' trees, about 

 1 inch long, % inch in diameter, rounded and slightly curved, composed of undigested 

 wood pulp. 



