308 Monograph of the Genus Sdurus. 



rel can be designated ; but in none is there greater than in the present. 

 All our naturalists seem to insist that we have a Sciurus niger, although 

 they have applied the name to the black varieties of several other species. 

 As the name, however, is likely to continue on our books, and as the spe- 

 cimens before me, if they do not establish a true species, will show a 

 very permanent variety, I shall describe them under the above name. 



" Dr. Godman states (Nat. Hist. vol. ii, p. 133), that the black squirrel 

 has only twenty teeth ; — the specimens before me have no greater num- 

 ber, with the exception of one, evidently a young animal, a few months 

 old, which has an additional tooth on one side, so small that it appears 

 like a white thread, the opposite and corresponding one having already 

 been shed. If further examinations go to establish the fact, that this 

 additional molar in the northern grey squirrel is persistent, and that of the 

 present deciduous, there can be no doubt of their being distinct species. 

 Its head appears to be a little shorter and more arched than that of the 

 grey squirrel, although it is often found that these differences exist among 

 different individuals of the same species. Incisors compressed, strong, 

 and of a deep orange color anteriorly. Ears elliptical, and slightly 

 rounded at the tip, thickly clothed with fur on both surfaces, that on the 

 outer surface in a winter specimen, extending three lines beyond the mar- 

 gin : there are, however, no distinct tufts. Whiskers a little longer than 

 the head ; tail long and distichous, thickly clothed with moderately 

 coarse hair. 



" The fur is softer to the touch than that of the northern grey squirrel. 

 The whole of the upper and lower surface, as well as the tail are bright 

 glossy black ; at the roots the hairs are a little lighter. The summer 

 specimens do not differ materially in the color of their fur from the win- 

 ter ones, except that they are not so intensely black. In all the speci- 

 mens I have had an opportunity of examining, there are small tufts of 

 white hairs irregularly situated on the under surface, resembling those on 

 the body of the mink. There are also a few scattered white hairs on the 

 back and tail. 



Dimensions. 



" Length of head and body, . . . 



" of tail (vertebrrs), 



" including fur, . , , 

 Palm to end of middle fore claw, . 



Length of heel to the point of middle claw, . 



" of fur on the back, . . . 



Breadth of tail with hair extended, . . 5 



" Geographical Distribution. — The specimens from which this de- 

 scription has been taken were procured, through the kindness of friends, 



