MAMMALIA. 
33 
The principal dimensions of the above animals are as follows : — 
Specimen from 
Buenos Ayres Maldonado. Valparaiso. East Falkland. East Falkland. Keeling Island. 
In. Lines. In. Lines. In. Lines. In. Lines. In. Lines. In. Lines. 
Length from nose to root of tail .99 93 86 89 90 83 
of tail Imperfect 6 0 6 6 Imperfect 6 0 6 6 
of tarsus 17 17 17 17 17 17 
Upon comparing the skull of the Valparaiso variety with that of a British 
specimen of Mus decumanus, I could perceive no difference. A skull from West 
Falkland did not differ, neither did the dentition of the Keeling Island specimen 
above noticed. A perfect specimen of this last I have not had an opportunity of 
examining. 
2. Mus (decumanus var. ?) maurus. 
Mus maurus, Waterh. in Proceedings of the Zoological Society of London, for February, 1837, p. 20. 
M. pilis supra purpurescenti-nigris ; sub t us plumb eis ; auribus parvulis, pallide fuscis: 
cauda corpus fere cc quant e. 
Description. — The character of the fur of this animal nearly resembles that of 
Mus decumanus ; it is, however, of a harsher nature : the general colour of 
the upper parts and sides of the body is purple-black, arising from the longest 
hairs being of this colour, and likewise the tips of those which are next in 
length ; the latter, however, excepting at the tip, are white, and this white 
is not entirely hidden, even when the hairs are in their ordinary position : 
on the head the hairs assume a brownish hue, and are tolerably uniform : the 
limbs, and under parts of the body, are of a deep gray colour, with a faint 
purple-brown wash : the under fur is gray : the ears are small, of a brown- 
white, or very pale brown colour, and furnished with minute brown hairs : 
the small, scattered, bristly hairs of the tail are of an uniform brownish-black 
colour. The hairs of the moustaches are black at the base, and grayish at 
the apex. 
In. Lines. 
Length from nose to root of tail . .11 3 
of tail . . . . .76 
of tarsus 18 
Habitat, Maldonado, La Plata, (June.) 
In. Lines. 
Length of ear 0 6£ 
from nose to ear . . . .22 
F 
