MAMMALS OP THE MEXICAN BOUNDARY. 269 



General notes. — The subgenus Armosc'mrus is chai-acteristic of tlie transition 

 zone In the mountains bordering the table-land of Mexico from Mts. Oiizuba 

 and Toluca northward. It is intrusive in the United States, where it is rep- 

 resented in Arizona and western New Mexico by a single species, S. arieonensis. 

 The group is most nearly related to Parasciurus, from which the skull charac- 

 ters distinguish it. The following species and subspecies belong to this sub- 

 genus : 8. oculatus, 8. o. tolucw, 8. alleni, 8. nayaritensis, 8. apache, 8. arizon- 

 ensis, and 8. a. Imaoliiicu. (Proc. Wash._Acad. Sci., I, 1899, p. 29.) 



SCIURUS ALLENI Nelson. 

 ALLEN SaXnUREL. 



"8ciiiriis caroliiiensi.1? ?" Baird, Mam. N. Am., 1857, pp. 263, 2G4 (Santa 



Catarina, Nuevo Leon, Mexico). 

 SeiKrns caroliiwiisis var. carolinensis, Allen, Mon. N. Am. Rodentia, 1877, 



pp. 700-709, 716 (part: from Nuevo Leon, Mexico). 

 8ciunis earolinensin. Alston, Proc. Zool. Soc. London, 1878, pp. 658-659 ; 



Biol. , Cent-Am., Mam., pp. 124, 125, June, 1880 (part: from Nuevo 



Leon, Mexico). 

 8eiuriin urhoiiriiKiN. Allen, Bull. Am. Mus. Nat. Hist., N. Y.# III, May, 



1891, p. 222 (part: from San Pedro mines, Nuevo Leon, Mexico). 

 8ciurus alleni Nelson, Proc. Biol. Soc. Washington, XII, 1898, pp. 147, 148, 



June 3; Proc. Washington Acad. Sci., I, 1899, p. 91, May 9 (Kevisiou 



of the Squirrels of Mexico and Central America). — Miller and Rehn, 



Proc. Bost. Soc. Nat. Hist, XXX, Pt. 1, Dec. 27, 1901, p. 35 (Syst. 



Results Study N. Am. Mam. to close of 1900). — Elliot, Field Col. Mus., 



Zool. Ser., IV, Pt 1, 1904, p. 108 (Mam. Mid. Am.). 



As long ago as 1857 Baird suspected that this species might be dis- 

 tinct from the common eastern gray squirrel to which it bears a very 

 close resemblance externally. Lack of material for comparison pre- 

 vented him from naming it, however, and it was first described by 

 Nelson as follows : 



Type-locality. — Monterey, Nuevo Leon, Mexico. Type no. |f}|^ U. S. National 

 Museum, Biological Survey collection. 



Distribution. — Open pecan and other forests of Lower Sonoran zone near 

 Monterey, Nuevo Leon, extending up to oak and pine forests of Transition zone 

 near Victoria and Miquihuana, Tamaulipas, Mexico (alt., 2,000-8,500 ft.). 



Characters. — Upper parts nearly uniform grayish brown or yellowish brown, 

 much as in 8ciurus curoliiiensis ; feet gray; under parts white. Pelage on 

 back soft and rather dense ; tail rather full. Teats : p. \, a. |, i. ];. 



Color. — Winter iielage : fcntire upper parts yellowish brown, finely grizzled 

 with gray and black, usually darker along back and grayer along sides ; top of 

 head similar, but usually a little darker ; eye with distinct ring of dingy whitish 

 shaded with buff on outer border ; sides of head grizzled dusky gray, often suf- 

 fused with yellowish brown ; ears and basal patch brownish gray ; fore feet 

 and outside of fore legs whitish gray, frequently more or less washed with 

 buffy ; hind feet whitish gray, usually with a spot of dark buffy on middle of 

 upper surface; outside of thighs like flanks, but often with a browner shade 

 near feet ; under parts white ; colpr of upper and lower parts usually separated 

 by a narrow line of pale grayish; base of ta'l all around like back; tail above 

 black, heavily washed with white, the yellowish brown or yellowish gray under 



