764 MONOGRAPHS OF SOUTH AMERICAN UODENTIA. 



This species, in size, proportions, and in the color of the dorsal surface, 

 is almost inseparable from var. rufonigcr of /S. a?stua?is ; it is, however, readily 

 distinguishable from that species by the generally almost wholly gray color of 

 the ventral surface, over which the hairs are conspicuously dusky at the base, 

 and by the white instead of red edging of the tail. It furthermore has two 

 premolars, the first quite large for a Sciurus, while in the large number of 

 specimens of both varieties of S. astuans I have examined I have found uni- 

 formly only one. It is so wholly distinct from all the other Sciuri as to require 

 no detailed comparison with any of them. 



The seven specimens of this species before me vary in respect to color- 

 ation as follows: — One (No. 7849, Orizaba, Mexico) is pure gray below through- 

 out, the hairs being tipped with white and dusky at base; above, olivaceous- 

 dusky, minutely punctulated with yellowish-rufous; middle of the back 

 blackish; ear-patch whitish. No. 7206, also from Orizaba, is similar, except 

 that the sides are rather more strongly varied with yellowish-rufous, and the 

 pectoral region is distinctly washed with fulvous. No. 8491, from near Cor- 

 dova, is almost exactly like the last, being perhaps rather more fulvous below 

 and a little redder on the flanks. Another (of which the label is lost) is still 

 more rufous above and more fulvous below. No. 8490 (Cordova) is like the 

 last, with, however, distinctly white ear-patches. No. 3922 (Mexico) is more 

 rufous above, and is washed strongly with reddish-fulvous below. No. 3261 

 (Mexico) is bright orange below, but above is wholly like the gray-bellied 

 specimens from Orizaba. No. 8620, from Central Guatemala, is fulvous- 

 washed below, but is strongly ferrugineous above, with reddish-yellow ear- 

 patches, the prevailing color dorsally being ferrugineous, slightly varied with 

 black. In this specimen, the hairs of the dorsal surface are double-ringed 

 with fulvous, plumbeous at base, then a narrow ring of fulvous, followed by 

 another of black, and tipped with rusty. In all the other specimens, the 

 hairs are wholly blackish, except the tip, which is yellowish, varying more or 

 less in different specimens to rufous. 



( )t the eight specimens of this species before me, seven are from 

 Southern Mexico and the other from Guatemala. Dr. Gray refers to his 

 M. tsphrogaster specimens from "Mexico (Salle), Guatemala (Salvin), Hon- 

 duras (Dyson), and Bogota (II. E. Strickland)''; I also refer to the same 

 species his M. Ueniurus from Guatemala, his M. middellinensis from Antio- 

 guia, New Granada, and less confidently his M. fraseri from Ecuador. The 

 first three of these names I think arc unquestionably referable to this species. 



