660 



THE MONTHLY BULLETIN. 



Measurements. — Average and extreme measurements, in millimeters, of twenty 

 mature specimens from the Yosemite section of the high Sierra Nevada are as 

 follows: Ten males: total length, 263 (230-280) ; tail vertebrae, 66 (60-74) ; hind 

 foot, 44 (41-45.5) ; ear from crown, 9 (7-11) ; greatest length of skull, 44.5 

 (42.2-46.3) ; zygomatic breadth, 28.0 (26.4-29.5) ; interorbital width, 10.5 (9.7-11.0). 

 Ten females: total length, 260 ( 240-288) ; tail vertebrae, 66 (55-74) ; hind foot, 43 

 (40-46) ; ear from crown, 10 (8-13) ; greatest length of skull, 44.0 (41.3-46.5) ; 

 zygomatic breadth, 28.2 (26.7-28.9) ; interorbital width, 10.4 (9.7-11.0). 



Relatively old individuals show greatest size, especially of skull, which also has 

 acquired more conspicuous ridges and sharper angles. Males average a trifle larger 

 than females. 



Weights. — Average and extreme weights, in grams, of twenty mature specimens 

 from the Yosemite section of the high Sierra Nevada are as follows : Ten males, 222 

 (125.5-285.0) ; ten females, 240 (172-305). Average, in ounces, both sexes, about 8. 



The example showing the least weight was fully adult, but was very lean. Like 

 other ground squirrels this species varies greatly in weight according to the amount 

 of fat present. Specimens taken in August and September are, as a rule, fattest. 



Type locality. — Donner, Placer County, California (Merriam, 1888, pp. 317-320). 



Distribution area. — Higher parts of the central Sierra Nevada (chiefly Hud- 

 sonian life-zone), from vicinity of Independence Lake, Nevada County, south to 

 southeastern border of Yosemite National Park in vicinity of Mount Lyell (see fig. 

 18). Altitudinal range, from 11,800 feet (as on Mt. Conness) down on western 

 flank of Sierras to as low as 8,100 feet (Porcupine Flat, Yosemite Park) ; on easte n 

 flank to as low as 6,500 feet, at western border of Mono Lake (Mus. Vert. Zool.). 



Specimens examined. — A total of 48 from the following localities in California: 

 Nevada County: Independence Lake, 13. Placer County: "Johnson's Pass, High 

 Sierras" [= Summit], 1. El Dorado County: Mt. Tallac, 1. Alpine County: Hope 

 Valley, 4. Mono County : Mono Lake P. O., 1 ; Farrington's, Mono Lake, 3 ; Mono 

 Pass, 1 ; Tioga Pass, 1 ; Walker Lake, 1. Tuolumne County : Tuolumne Meadows, 8 ; 

 middle Lyell Canyon, 1; head Lyell Canycn, 5. Mariposa County: Mt. Hoffman, 

 10,700 ft, 1; Tioga Road, southeast Mt. Hoffman, 3 ; near Vogelsang Lake, 2; two 

 miles east Porcupine Flat, 1; one mile east Lake Merced, 1. 



This species of ground squirrel was named after Lyman Belding, an 

 early resident of Stockton and a naturalist of considerable attainment. 

 Belding found it in the summer of 1885 in the vicinity of Summit, 

 Placer County, and ;sent a specimen to Dr. C. Hart Merriam, who later 

 (1888) described the species, calling it Spermophilus beldingi. 



The most notable thing about the Belding Ground Squirrel is the 

 great altitude of most of the area it inhabits. It is very closely restricted 

 to the alpine meadows of the high central Sierra Nevada. The warmer 

 levels below seem to be just as inimical to its welfare as the cold upper 

 zones certainly are to the other ground squirrels which inhabit the 

 middle slopes or foothills. Reference to our diagram (fig. 23) will 

 show some interesting facts in this regard. We would infer that the 

 Belding Ground Squirrel is the hardiest of all our species as regards 

 ability to endure long and cold winters, though here the habit of hiber- 

 nation must come importantly into play as tiding it over the extremes. 



This squirrel occurs in fair abundance on the preferred portions of 

 its general range, namely, the grassy meadows in the neighborhood of 

 timber line. Individuals rarely occur down as low as the belt of red 

 firs and aspens (Canadian zone) on the west slope of the Sierras, though 

 on the east slope a few do occur down through the Jeffrey pine belt. 

 It is quite strictly an inhabitant of open levels; it is rarely or never 

 seen in the woods or on steep or rocky slopes. Occasionally an indi- 

 vidual ascends to the top of some glacier-borne boulder out in a meadow 

 for a look around, but we have yet to observe any greater exploit in 

 climbing. 



08 



