SCIURIDA—SCIURUS COLLIAI. 739 
pure white; no lateral line. Tail long and very broad, vertebra alone 
nearly equal in length to the length of head and body; above, deep black, 
broadly edged with whitish or mixed white, black, and pale fulvous; beneath 
with or without a broad central area of bright tawny, bordered by a broad 
subterminal band of deep black, and broadly edged with white. Sometimes 
the central bright tawny zone can be faintly seen through the hairs of 
the dorsal surface, as in the Arizona specimens; again it is merely pale ful- 
vous, striped with narrow lines of dusky, the central fulvous area being visi- 
ble only from the lower surface. 
This species is thoroughly distinct from S. carolinensis, which it some- 
what resembles in color, as it also apparently is from every other North 
American species of Scturus. It was described by Richardson, in 1839, from 
a specimen from San Blas, on the west coast of Mexico, in latitude 21° 34’, 
where Mr. Collie found it common. My Mazatlan specimens are from near 
the same locality (about one hundred miles farther north), and agree with 
Richardson’s original description. Dr. Gray’s S. colli@i, “var. 2”, with bright 
rufous sides and limbs and white belly, I refer with little hesitation to S. 
boothiz, while his “var. 1”, from the west coast of South America, with “the 
under surface yellow”, he considers the same as Ogilby’s S. variegatoides and 
his S. griseocaudatus, both of which I refer to the S. hypopyrrhus of Wagler. 
The “ Macrozus colliai” of Gray seems to be only in small part referable to 
the S. collizi of Richardson. 
I refer to this species also the S. arizonensis of Coues, described origin- 
ally from a single specimen obtained at Fort Whipple, Ariz. Two other 
specimens from Arizona, collected later by Mr. F. Bischoff, agree essentially 
with Dr. Coues’s specimen, except that they are somewhat larger. One of 
them, however, has the brownish dorsal area less strongly developed than in 
the others, and has the lower surface considerably varied with irregular 
patches and streaks of pale yellowish-rufous, thus showing a tendency to the 
acquisition of a rufous belly, so common a feature among the Squirrels of 
Mexico and Central and South America. Dr. Coues’s specimen, though killed 
in December, was evidently not full-grown, being, as described by him, of 
about the size of S. carolinensis. The other specimens, one of them a female 
that had recently nourished young, are much larger, and indicate a species 
fully as large as S. aberti, if not even larger. 
The coloration of S. col/igzi, at first sight, seems to bear a close resem- 
