1878.] MR. E. R ALSTON ON NEOTROPICAL SQUIRRELS. 659 



there are specimens from Nuevo Leon in the National Museum at 

 Washington. Mr. Allen's " var. yucatanensis'" is based on speci- 

 mens collected at Merida, which agree in their pale coloration, the 

 absence of rufous on their flanks, their small size, and the compara- 

 tive coarseness of their pelage. He considers that this form is 

 "possibly specifically distinct," but remarks that the Nucvo-Leon 

 examples are fairly intermediate ; and, judging from the single 

 typical example which Mr. Allen kindly lent me, I think he was 

 wise in refusing it specific rank, at least for the present. 



Of the geographical variations presented by the Grey Squirrel 

 throughout its very extensive range, Mr. Allen observes they consist 

 "mainly in decrease in size southward, and an increase in in- 

 tensity of coloration, the whitish tips of the hairs of the dorsal 

 surface seen in northern specimens being replaced by yellowish- 

 brown in the southern ones, except in the case of var. yncata- 

 nensis." The decrease in size as we go southwards is of course 

 strongly in favour of the distinctness of the next species. 



II. SCIURTJS ARIZONENSIS. 



*Sciurus arizonensis, Coues, Amer. Nat. i. p. 35/ (1867). 

 (Scivrus collicei, Allen, Mon. N.-Am. Rodent, p. 738, nee 

 Richardson.) 



Length about 12\50, of tail-vertebne 11 inches. Upper parts 

 grey, more or less mixed with yellowish-brown, especially along 

 the middle of the back ; lower parts pure white. Tail long, very 

 bushy, strongly washed with white, the hairs tawny or fulvous with 

 two narrow and one broader black band, succeeded by a long white 

 tip. 



Hub. Arizona; California; Mexico. 



Misled by imperfect descriptions and a bad figure of Richardson's 

 type, Mr. Allen has referred the Arizona Squirrel of Dr. Coues to 

 Richardson's S. collicei. He has since kindly intrusted me with a 

 typical example of >$. arizon-nsi* ; and I find that it is quite distinct 

 from S. collicei (which is Mr. Allen's 5. boothice), being much more 

 nearly allied to S. carolinensis, from which, however, both Dr. Coues 

 and Mr. Allen consider that it is " thoroughly distinct." Tlie 

 superior size, coloration of the long heavy tail, and absence of a lateral 

 line appear to be constant, but in some specimens in the Paris and 

 British Museums the grey of the upper flanks is not so clear from 

 rufous as in the examples described by Mr. Allen. The example 

 mentioned by that gentleman as having "the lower surface consi- 

 derably varied with irregular patches and streaks of pale yellowish 

 rufous" gives support to the opinion that furthur material will 

 render it necessary to unite the next species with the present. If 

 so, Dr. Coues's name must be retained, as it has priority over Gray's 

 title. 



