SQUIRRELS OF MEXICO AND CENTRAL AMERICA 39 



Distribution. — Arid tropical lowlands and adjacent mountains of 

 southern Tamaulipas, northern Vera Cruz, eastern San Luis Potosi, 

 eastern Qiieretaro and Puebla, northeastern Hidalgo, and thence south 

 to border of Humid Tropical zone in central Vera Cruz, and northern 

 side of Isthmus of Tehuantepec in Oaxaca. (Usually below 4000 ft. 

 alt., but sporadically up to over 8000 ft. in Hidalgo and Queretaro.) 

 Characters. — Size large ; color of back pale grizzled gray with nape 

 patch poorly defined, rusty or yellowish brown; underparts bright 

 ferruginous, this color extending up over fore legs and costal area 

 nearly or quite to top of shoulders. Tail long, flat, and rather slender; 

 hairs on back rather coarse and glossy. Teats : p. \ a.| i. \. 



Color. — Top of nose and fore part of crown iron gray ; nape patch 

 often indistinct and varying from dull yellowish brown to dull rusty 

 rufous, generally grizzled with gray or whitish; rest of upperparts in- 

 cluding upper cheeks, sides and top of neck (below and behind nape 

 patch) a median line between shoulders, entire lumbar region, rump 

 and outside of thighs varying from dark iron gray to pale whitish gray ; 

 fore feet and sometimes outside of fore legs iron gray, usually darker 

 than back ; hind feet varying from blackish faintly grizzled with gray to 

 iron gray like back ; sides of nose, lower cheeks and chin pale grizzled 

 gray ; rest of underparts bright ferruginous, this color usually extend- 

 ing over outside of fore legs and high up over costal area, sometimes 

 even meeting and forming a band across top of shoulders ; base of tail 

 all around like back; rest of tail above black washed with white; be- 

 low, with a broad median band of ferruginous, bordered by a line of 

 black and edged with white ; ring around eye dark buff, with an area 

 of dull yellowish brown extending back nearly or quite to base of ear ; 

 ears gray like crown, or rusty reddish like nuchal patch ; ear patches 

 (usually absent in summer) dingy gray or whitish. Hairs on back 

 black, with broad white tips, often mixed with others having broad 

 median and sometimes basal yellow rings. The winter pelage differs 

 from that of summer mainly in paler upperparts and distinct whitish 

 ear patches. 



Variation. — Sciurus atireogaster presents a wide range of varia- 

 tion. The underparts range from bright ferruginous to dark ru- 

 fous, almost like the color of S. hypopyrrhus. The back varies 

 from whitish to dark iron gray. The upward extension of ferrugi- 

 nous on the sides varies from a slight wash just back of fore legs to 

 a broad band reaching over costal area and across top of shoulders, 

 covering nearlv half of the body. 



A specimen from Orizaba in the U. S. National Museum has the 



