126 GLIRES. 
Fort Whipple, in Arizona’. It is closely allied to the last species, from which, 
however, both Dr. Coues and Mr. Allen consider it to be “thoroughly distinct.” The 
superior size, the coloration of the long heavy tail, and the absence of any lateral line 
appear to be constant; but in some specimens in the British and Paris Museums the 
grey of the upper flanks is not so clear from rufous as in the examples examined 
by Mr. Allen‘. The specimen described by that gentleman as having “ the lower 
surface considerably varied with irregular patches and streaks of pale yellowish rufous” 
gives support to the idea that further material will enable us to unite the next species 
with the present. In that case the name S. arizonensis will stand, Dr. Coues’s descrip- 
tion having priority over Gray’s. 
In the “ Monographs of the North-American Rodentia” Mr. Allen was unfortunately 
misled, by imperfect descriptions and a bad figure, into identifying the Arizona 
Squirrel with Richardson’s Sciwrus colliwi*. His kindness in lending me one of the 
typical specimens of S. arizonensis enabled me to point out this error?, which he has 
promptly rectified in his ‘“‘Synonymic List of the American Sciurt”?. 
3. Sciurus griseoflavus. 
Macroxus griseoflavus, Gray, Ann. & Mag. Nat. Hist. 3rd ser. xx. p. 427 (1867, descr. orig.)*. 
Sciurus griseoflavus, Alston, P. Z. S. 1878, p. 660°; Allen, Bull. U.S. Geol. Surv. iv. p. 880°. 
? Sciurus ludovicianus, Tomes, P. Z. 8. 1861, p. 281 (nec Custis)*. 
Hab. Mexico (Liebmann, Mus. Hafn.); Guaremaua, Duefas (Salvin*), Volcan de Fuego 
(Godman & Salvin, Mus. Brit.), Coban (Boucard, Mus. Paris). 
[ have pointed out elsewhere? that the types of Gray’s Macroxus griseoflavus are 
quite distinct from those of his J. leucops (with which Mr. Allen had confused them 
in his Monograph), and appear to me to be either very nearly allied to the last species, 
if not identical with it. They differ from typical specimens of S. arizonensis in colour, 
the upper parts being yellowish grey and the lower parts yellowish red. But, as above 
mentioned, some specimens of the northern form seem to show a tendency to vary in 
this respect ; and, judging from the analogy of other species, it seems highly probable 
that the two races will be found to intergrade. Mr. Allen observes that, in view of my 
diagnosis of S. griseoflavus, his inclination is to unite it with S. arizonensis, but that he 
refrains from doing so at present?; and till further material is forthcoming this appears 
to be the only proper course. 
I have not been able to discover in the British Museum the Guatemalan specimens 
which Mr. Tomes referred to S. ludovicianus*; but it appears probable that they be- 
longed to the present species, which has a general resemblance in colour to some of 
the numerous varieties of the Fox Squirrel. In this I am confirmed by Mr. Salvin, 
who tells me that he believes that Mr. Tomes applied the name to specimens of this 
Squirrel obtained by him in the oak-forests of the Volcan de Fuego, where he found it 
