MAMMALS OF THE MEXICAN BOUNDARY. 27 1 



Hciiirus tiiiuchc Allen, Bull. Am. JIus. Nut. Hist., V, p. 20, Miii-cLi 1(J, 180;i 

 (original doscTiptiou).— Nelson, Proc. Washington Acad. Sci., I, p. 04, 

 May 9, 1809 (Revision of the Squin-els of Mexico and Central Amer- 

 ica).— Milleb and Rei-in, I'roc. Bo.st. Soc. Nat. Hist, XXX, No. 1, 

 Dec. 27, 1901, p. 36 (Syst. Results Study X. Am. Mam., to close of 

 1900) .—Elliot, Field Col. Mus., Zool. Ser., II, 1901, p. 58 (Syuop. Mam. 

 N. Am.) ; IV, Pt. 1, 1904, p. 110 (Mam. Mid. Am.). 



Type-locality.— T\iis, species is based on two skins and skull taken 

 m northern Chihuahua by the Lumholtz Expedition. (Type, skin 

 and skull, in the American Museum of Natural History.) 



Geographical j-an^e.— Forested areas in the Elevated Central 

 Tract, between the Colorado Plateau and the Plateau of Mexico, in 

 the Transition zone. 



Description.-— This splendid squirrel has the general appearance 

 of a fox squirrel, and like it lacks the front upper premolar. In- 

 stead of a small, pallid animal, like Sclnrus ruftventer texianus, it 

 is of about the size of typical Scinrus rupoenter and a strongly- 

 colored form. In winter there is a broad band of black extending 

 from the crown to the root of the tail ; this is seasonal, however, and 

 disappears with the incoming of the post-breeding pelage. The sides 

 of the head and body are yellowish gray mixed with black. Orbi- 

 tal ring, feet,' and under surface of body ochraceous. Ears rusty 

 drab, ochraceous around the meatus. Tail with all the hairs ochra- 

 ceous at base; those of the median area below ochraceous through- 

 out; those above ochraceous at extreme base, then black almost to 

 the extremity, which is yellowish white, and those of the sides ochra- 

 ceous at base, pale yellowish at end, and black in the middle, the three 

 bands being of approximately equal width. The naked soles of the 

 feet are dark purplish. Iris very dark brown. 



The summer or post-breeding pelage of this squirrel is quite dif- 

 ferent from the winter pelage described above. There is no black 

 ■ dorsal area, and the animail more closely resembles Sciurus rvfi reci- 

 ter. When this coat is new the black central area of the upper 

 side of the tail is obscured by ochraceous tips to the hairs, and the 

 pelage of the upper surface of the body, though with much black on 

 the hairs, is sufficiently annulated with fulvous and pointed with 

 hoary tips to produce a grizzled effect. 



Seasonal changes. — Three adult males taken on the San Luis 

 Mountains, July 11, 12, and 13, 1892, were in worn winter jjelage ; 

 but this was being replaced to a greater or less extent, on both upper 

 and lower surface, ,by the pepper-and-salt summer coat. An adult 

 female* (No. ffffl, U.S.N.M.), taken July 11, 1892, with the males 

 just mentioned, had almost completely changed to the summer 

 pelage, except on the thighs and tail. An adult female (No. 58904, 



aMammsB, 4 pairs (P. \, A. f , I. \). 



