MAMMALIA. 
55 
unable to satisfy myself whether they are varieties of Mus xanthorhinus or 
not. Both of Mus canescens and of Mus xanthorhinus , I have before me what I 
imagine to be an adult and a young specimen. The adult and the young of 
M. xanthorhinus agree in being of a yellowish-brown colour, and in having the 
muzzle and tarsi deep yellow ; both specimens of Mus canescens are of a gray 
colour, with an indistinct yellow wash, the muzzle and tarsi being tinted with 
yellow, as in M. xanthorhinus. Besides this difference in tint, which, perhaps, 
is unimportant, M. canescens differs from M. xanthorhinus in having the head 
larger, the tail rather longer, and the fur less soft. The specimens of this animal 
are both from Patagonia ; one of the specimens of Mus xanthorhinus was brought 
by Mr. Darwin from Terra del Fuego ; and as the other formed part of Captain 
King’s collection, it in all probability came from the same locality. As I only 
possess one skull, I cannot speak with certainty as regards the size of the head ; 
the difference, however, in the stuffed specimens is considerable, and it is strange 
that each of the pairs should agree so perfectly, supposing the difference to be 
the work of the stuffer’s hands. 
18. Mus LONGIPILIS. 
Plate XVI. 
Mus longipilis, Waterh., Proceedings of the Zoological Society of London for February 1837, p. 16. 
M. supra obscurb griseus , jlavo lavatus ; subtiis griseus ; pedibus fuscis, unguibus 
longiusculis ; auribus mediocribus ; cauda corpore breviore, supra nigrescente, subtiis 
fuscescente ; rhinario sub-producto : vellere longissimo, molli. 
Description. — Fur very soft and silky, and extremely long — the ordinary fur of 
the back measuring nearly three quarters of an inch, and the longer hairs 
one inch in length ; ears moderate ; tail nearly as long as the body ; muzzle 
much pointed ; general colour gray, washed with yellow, the under parts 
pale gray, or grayish white ; feet brown ; ears and tail well clothed ; the 
hairs on the inner side of the ears are chiefly of a yellow colour, those on the 
upper surface of the tail are brown black, those on the under part are dirty 
white ; the hairs of the back are deep gray at the base, broadly annulated 
with yellow near the apex, and dusky at the apex ; the longer hairs are 
grayish black ; the hairs of the moustaches are dusky at the base, and 
whitish beyond that part ; the claws are long, and but slightly curved ; the 
