SCIDKID^-SCIURDS DUDSONIDS AKD VABa 



G83 



brownish-red, and iu the central portion of the tail being also dark brownish- 

 red, with the enclosing black bar much broader and purer black and more 

 narrowly fringp-d with yellowish. Ofleii the terminal half of the tail is almost 

 wholly black. 



Var. oouglatsi generally diflferg little in the general color of the dorsal 

 Rurfacc i'rom var. ricliardaoni, being, on the whole, rather darker or more 

 fuBCor.g. The tail, however, is less black, and is more broadly fringed with 

 yeUdwish-white. The central portion (dorsally) is generally less strongly 

 fcrruginoufi, varying sometimes to gray. The ventral surface of the body, 

 however, is tawny, thus furnishing, in typical examples, a very obvious 

 distinctive feature. 



Yar. fremonti generally lacks the central dorsal stripe, and the fulvous 

 of the upjier surface inclines more strongly to yellow. The tail is generally 

 gray centrally above (sometimes more or less fulvous or rufous), with a broad 

 enclosing zone of black, broadly fringed with pure white. 



These vorieties, in theirextreme phases, appear very distinct, yet wherever 

 their respective habitats meet their characters become very much blended. 

 Thus, as alreody noted, in Northwestern Wyoming, where meet the habitats 

 of varieties hudnonius, rkhardsoni, andfremonti, a considerable proportion of 

 the specimens received from this region can scarcely be referred to one of 

 the varieties rather than to another. Many of the specimens present distinctly 

 traces of the leading characteristics of the three forms ; others, while present- 

 ing considerable resemblance to hudnonius, incline most strongly to var. 

 rkhardsoni; others, again, toward fremonti. Others still, both from this 

 region and from localities much farther westward, combine the leading 

 features of ^ars. richardaoni and fremonti. Specimens from the region where 

 the habitats of richardtoni and douglassi meet are again variously intermediate 

 between these two forms, being generally distinguishable only by the color of 

 the ventral surface. In California, where the habitats of doug/utsi ai}d fre- 

 monii meet, the same localities furnish typical examples of each form, with 

 others variously intermediate between them. Professor Baird, in 1867, with far 

 leas material before him than has passed under the examination of the present 

 writer, in referring to the gray-tailed s|iecimens from California, says: — "In 

 this condition the tail exactly resembles, in every respect, that of S. fremonti, 

 and the two [iSi. douglasai and S. fremonti], comparing Nos. 1160 [S. douglassi 

 from the Upper Des Chutes] and 520 [S. fremonti from Sawatch Pass, 



