SCIUltlDiE— SCIURDS HUDSONIDS AND VARS. 683 



brownish-red, and in 1 he central portion of the tail being also dark brownish- 

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

 narrowly fringed with yellowish. Often the terminal half of the tail is almost 

 wholly black. 



Var. douglassi generally differs little in the general color of the dorsal 

 surface from var. richardsoni, being, on the whole, rather darker or more 

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

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

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

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

 distinctive feature. 



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

 of the upper 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 varieties, in their extreme phases, appear very distinct, yet wherever 

 their respective habitats meet their characters become very much blended. 

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

 of varieties hudsonius, richardsoni, and fremonti, 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 hudsonius, incline most strongly to var. 

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

 region and from localities much farther westward, combine the leading 

 features of vars. richardsoni and fremonti. Specimens from the region where 

 the habitats of richardsoni 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 douglassi and fie- 

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

 others variously intermediate between them. Professor Baird, in 1857, with far 

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

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

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

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

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



