64 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
This species is closely allied to the last, but differs in being rather smaller, in 
having smaller ears which are well clothed with hair, and not sparingly furnished 
as in Mus griseo-flavus, and in having a shorter tail which, like the ears, is more 
densely clothed with hairs ; in the structure of the molar teeth there also differ- 
ences which will be better understood by comparing the drawings. Fig. 16, a, 
Plate 34, represents the molars of the upper jaw, and 16, b, those of the lower 
jaw. 
“ Extremely abundant in the coarse grass and thickets in the ravines at Port 
Desire and Santa Cruz : was caught in a trap baited with cheese.” — D. 
25. Mus Darwinii. 
Plate XXIII. 
Mus Darwinii, Waterh ., Proceedings of the Zoological Society of London for February 1837, p. 28. 
M. supra pilis pallidb cinnamomeis et nigrescentibus intermixtis ; ante oculos cinerascen- 
tibus ; gems, lateribus corporis, et cauda prope basin, pallidb cinnamomeis ; partibus 
inferioribus pedibusquealbis ; auribus permagnis ; cauda caput corpusque ferb cequante, 
supra fusco-nigricante, subtus alba. 
Description. — Form robust ; ears immensely large ; tail nearly equal in length to 
the head and body taken together ; fore feet very small ; tarsi moderate ; fur 
very long and soft ; general tint of the upper parts pale cinnamon yellow ; on the 
rump a richer yellow hue prevails, and on the back there is a brownish tint, 
owing to the interspersed long hairs being of that colour ; the upper surface 
of the head is grayish ; the cheeks, like the sides of the body, are of a deli- 
cate yellow colour, faintly clouded with brown ; the sides of the muzzle, 
lower part of the cheeks and sides of the body, and the whole under parts, 
are pure white ; the feet and tail are also white, if we except the upper sur- 
face of the latter, which is dark brown ; the yellow tint of the sides of the 
body is extended downwards on the outer side of the fore legs and on the 
back of the hinder legs ; the ears are but sparingly furnished with hair, 
excepting on the fore part, externally, where they are of a brownish colour ; 
the minute hairs which cover the remaining parts of the ear are very pale ; the 
tail is well clothed with hairs ; the hairs of the moustaches are numerous and 
very long ; they are for the most part blackish at the base, and gray at the 
apex ; the incisors are rather slender, the upper pair are an orange colour, 
and the lower, yellow ; the hairs of the ordinary fur of the back are gray at 
