670 



THE MONTHLY BULLETIN. 



favorable. While our observations show them to be strictly diurnal in 

 habits, we have noted an apparent aversion to direct sunshine. Perhaps 

 this is because the sunshine on the desert is in summer so intense as to 

 be quickly fatal to any small animal exposed to it for long. We know 

 for a fact of squirrels caught in traps by one foot or merely a toe, on 

 open ground, which have quickly succumbed — "sun-cooked" is the 



Lower 

 6onoran 



Upper 

 donoran 



Transition 



Canadian Hudeon, 



Arctic 



Qikllu5 -beecheui beecheiji 



Cifellus beech eyi fich&ri 



Cife//u5 beechQLf'i nedoticuQ 



Cilellu.6 douglao/i 



Cifellus van'egatug grammuras 



Cifellus ore gonu6 



Ci/ellu5 beld/'ngi 



Cifellui> mollid slephensi 



Cifellus mohaVensis 



Cilcllus ferelicaudus fereficaudus 



Cifellus lerelicaudus erewonomua 



Cifellus iereficaudus chlorud 



Callospermophilus chrysodeirua chrgsodeirus 



Callospermophilus chrysodeirus perpalfidua 



Callospermophilud chrysodeirus bernardinus 



Qmmospermophilus feucurus feucurue 



Qmmospermophilue nelson! nelson! 



Qmmo6permopfiilu6 nelson i am pi u 5 



Fig. 23. Diagram showing the ranges of the ground squirrels of California accord- 

 ing to life-zones. (For life-zone map of California, see Grinnell, 1913, pi. 15.) 



term we use for such victims. At any rate, the squirrels are seen 

 crossing open spaces but momentarily, and thenceforth they remain in 

 the shade of bushes until they take final alarm and descend into their 

 burrows. 



The long, slender, ratlike tail is exclusively characteristic of this 

 species of ground squirrel. The body, too, is rather slender, though 

 after a full meal of green stuff individuals have been seen which showed 

 a rather pot-bellied outline. The mere rims of ears give the animal a 

 round-headed look. The movements are rather more agile than in most 

 of its relatives. It not infrequently climbs up into bushes to a height 

 of four or five feet, but here it becomes clumsy. 



The voice of the Round-tailed Ground Squirrel is unmistakable when 

 once learned. As far as known to us, but one kind of note is uttered, a 

 single high-pitched squeak or shrill whistle, seep, uttered only at rather 

 long intervals, never in a series as with some others of the ground 

 squirrels. The quality of this call is such that the direction from which 



78 



