THE GROUND SQUIRRELS OF CALIFORNIA. 



703 



Field characters. — Exactly the same as for the Nelson Antelope Ground Squirrel. 



Description. — General coloration in all pelages exactly as in nelsoni proper, but 

 clay color of upper surface a trifle paler, more buffy, and white side-stripes less dis- 

 tinct. Size somewhat greater, especially as regards ears. 



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

 full-grown specimens from twenty miles south of Los Banos, in western Fresno 

 County, are as follows : Ten males : total length, 246 (234-253) ; tail vertebra?, 73 

 (66-75) ; hind foot, 41 (40-43) ; ear from crown, 7.8 (7.0-9.0) ; greatest length of 

 skull, 41.8 (41.0-42.7) ; zygomatic breadth, 24.8 ( 24.0-26.2) ; interorbital width, 

 10.1 (9.4-10.4). Ten females: total length, 236 ( 230-243); tail vertebra, 73 

 (67-78) ; hind foot, 40 (37-43) ; ear from crown, 7.7 (6.5-9.0) ; greatest length of 

 skull, 41.2 (39.8-^2.0) ; zygomatic breadth, 24.3 (23.5-25.5) ; interorbital width, 10.0 

 (9.2-10.3). 



Comparison with the measurements given for nelsoni will show that amplus is 

 decidedly larger, with especially larger ear. 



Weight. — Only one record of adult weight is available, that of an old male, 186.3 

 grams (6£ ounces). 



Type locality. — Twenty miles south of Los Banos, Merced County [really near 

 mouth of Little Panoche Creek in Fresno County], California (Taylor, 1916, p. 15). 



Distribution. — Known as yet only from a limited section of the floor of the San 

 Joaquin Valley within 35 miles south of Los Banos, in southwestern Merced County 

 and northwestern Fresno County. Life-zone, Lower Sonoran. 



Specimens examined. — A total of 34 from the following localities in California. 

 Merced County : Sweeney's ranch in hills "22 miles south of Los Banos," 2. Fresno 

 County : mouth of Little Panoche Creek, 18 or 20 miles south of Los Banos, 29 ; 

 Hayes Station, B. M. 502, on Panoche Creek, 19 miles southwest of Mendota, 2 ; one 

 mile east of Mendota, 1. 



The Los Banos Antelope Ground Squirrel very closely resembles the 

 Nelson Squirrel, and is doubtless practically identical with that form 

 in general habits and locality preferences. More thorough exploration 

 will probably show that the distribution of the two is continuous, in 

 other words that the Los Banos race has resulted from a northward 

 extension of the ancestral stock which has allowed the acquisition of 

 the slight differences of greater size and paler tone of coloration which 

 characterize amplus. 



Along the western rim of the San Joaquin Valley south of Los Banos 

 this subspecies is common locally. The type series was taken by R. H. 

 Beck June 20, 1912, near the mouth of Little Panoche Creek, where the 

 animals were found occupying holes on common territory with Cali- 

 fornia Ground Squirrels. In one instance a " chipmunk " was shot at 

 the same hole with a ''ground squirrel." 



Near the point where Panoche Creek breaks out of the hills, a few 

 miles farther south, the last of June, 1918, museum collectors found a 

 few Antelope Squirrels along roads between barley fields. The cheek- 

 pouches of the two shot at the edge of such a field were full of barley 

 grains. The breeding season on both the above dates was long passed ; 

 young were nearly or quite full-grown. Remains of Ammospermophilus 

 were found about the mouth of the burrow of a kit fox, evidence of 

 the identity of one kind of enemy. 



The sort of country inhabited by this Ground Squirrel is arid and as 

 yet to but a small extent under cultivation. Water is not available for 

 extensive irrigation. The economic status already set forth for the 

 Nelson Squirrel probably also holds for the Los Banos race. 



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