92 



MONOGRAPHS OF SOUTH AMERICAN UODKNTIA. 



The absolute size and relative proportions of this species will be illus- 

 trated by the following table of measurements, and require no further remark. 



T m.i i: XXV. — Mi ttsuremi nis of twelve specimen* of IIksit.i.'omys .m'i;i;di.i <, 



We are unable to appreciate any differences whatever in the series of 

 skulls of this species as compared with a large number of those of leucopus. 



This elegant species may usually be distinguished at a glance from leu- 

 copus by the peculiar and beautiful tint of the fur — a rich golden-cinnamon, a 

 little darker from admixture of blackish hairs along the back; the ears like 

 the general color, this extending on the fore legs to the paws, and a faint wash 

 of the same tinting the under parts, between which and the upper parts the 

 line of demarkation is usually obscure, and often, as in No. 1580, from Knox- 

 ville, Tenn., inappreciable. The brighest-colored samples of leucopus we have 

 seen invariably lean to chestnut-fulvous, instead of the peculiar orange-fulvous 

 of aureolus. The difference in the shade is bard to express in words, but it 

 catches tin 1 eye at once. These brighter leucopus, moreover, have the cars 

 dusky and the under parts snow-white, while in aureolus the orange tinges 

 both these in a perceptible degree. The tail is but little paler below than 

 above, with rarely, if ever, a line of demarkation. 



While there is no question of the positive difference of this species from 

 leucopus, even the small series before us shows considerable variation. In No. 



