740 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



blance lo that of northern specimens of S. carolinensis, particularly to those 

 with a large brownish dorsal area. A careful comparison, however, shows 

 the absence of the fulvous suffusion below the surface of the pelage seen in 

 that species, and the absence of any tawny lateral line. The tail also is much 

 longer, and more than one-third fuller and broader, with quite different col- 

 oration, being distinctly tricolored below, with the three colors strongly con- 

 trasted and sharply defined, — centrally a broad band of bright tawny, nearly 

 two inches wide, with indications of two narrow bars of black within it on 

 each side of the vertebra;; outside of this is a band of deep black, one-half 

 to one inch wide, with, beyond this, a broad clear white margin. The hairs 

 are, many of them, fully three inches in length, so that the tail, measured 

 across the middle from point to point of the outstretched hairs, has a breadth 

 of six inches. The Mazatlan specimens have the tail rather less full, and 

 the bright tawny central area is simply pale fulvous, — a difference of no 

 great importance, in view of the differences in this respect presented by 

 specimens of S. carolinensis from even a single locality. 



The ears are low, broad, and round, not half as large as in S. aberti, and 

 less pointed, shorter, and broader than in S. fossor. This species is further 

 distinguished from S. fossor by its shorter tail, more brownish-gray color of 

 the upper surface, and by the presence of a yellowish-brown dorsal area, 

 covering nearly all of the back. S. collicei is distinguishable from S. aberti 

 not only through the great difference in the size and form of the ears and 

 the absence of ear-tufts, but by lacking the black lateral line, and by the 

 dorsal brownish area being pale yellowish-brown instead of reddish-brown or 

 chestnut. The S, leporinus of Audubon and Bachman, from "California", 

 greatly resembles jS. colliai in color, size, and form, and is, I have little doubt 

 referable to this species. Its supposed locality is doubtless wrong, being 

 not the present State of California, but from some point farther southward. 

 I have seen, however, a specimen of 8. fossor, in an evidently abnormal con- 

 dition of pelage, corresponding quite well with the description of S. leporinvs. 

 The description of Sciurus oculatus of Peters, in respect to size, colora- 

 tion, relative length of the tail, etc., agrees with the usual phase of S. collicd. 



