SCIUIIID^E— SPERMOPIIILUS GRAMMURUS AND VARIETIES. 829 



becomes worn off on the posterior part of the back, leaving exposed the 

 dull brownish under fur. In consequence of the wearing-off of the ends of 

 the hairs, the natural surface-markings wholly disappear, and give place to a 

 uniform tint of faded dingy-brown. 



As shown by the appended measurements of the skulls of this variety, 

 the largest specimens come from the mountains of New Mexico. 



Var. BEECHEYI. 

 Beechey's Spermophile ; Californian " Ground Squirrel". 



Varietal chars. — Rather smaller than var. grammurus ; similar in form 

 and general details of structure, differing mainly in coloration, the gray man- 

 tle being divided mesially by a rather wedge-shaped, broad area of brownish. 

 The gray is thus limited to two broad bands on the sides of the neck and 

 shoulders, extending from the occiput to the posterior edge of the scapula?, 

 or even beyond the middle of the body. The dark area by which they are 

 separated is narrow at the nape and slowly widens posteriorly. These lateral 

 bands of gray are sometimes quite narrow, sometimes very wide, nearly meet- 

 ing along the dorsal line over the scapular region. Through such specimens, 

 a complete intergradation may be traced into the mantled form of var. gram- 

 murus. No. 3621, from Fort Tejon, has the gray of the mantle strongest 

 on the nape, with no indication of a division, and is, in this respect, precisely 

 like No. 9568 from Soda Springs, Colo. Except in respect to the quite con- 

 stant feature of the more intense gray of the sides of the shoulders, separated 

 mesially by brown, the coloration of var. beecheyi is like that of var. gram- 

 murus, with parallel variations in respect to the depth and relative proportions 

 of the prevailing tints. 



Habitat. — West of the Sierra Nevada Mountains, from Northern Cali- 

 fornia southward into Mexico. 



In respect to size, fifteen skulls of var. beecheyi give an average length 

 of 2.20 against an average length of 2.40 in nine skulls of var. grammurus. 

 The largest skulls of var. beecheyi overlap the smaller of var. grammurus. In 

 all the details of structure, the skulls of the two forms are indistinguishable. 



Var. douglassi. 

 Douglass's Spermophile. 

 Varietal chars. — Intermediate in size between vars. grammurus and 

 beecheyi. Differs from beecheyi, in color, in the mesial space between the 



