46 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
The principal points of distinction between this and the two preceding 
species are pointed out in the account of M. elegans. 
Upon comparing the skull of M. gracilipes (PL 34, fig. 4. a.) with that of Mus 
Musculus, the most striking differences consist in its shorter and broader form, the 
upper surface being more arched, the interparietal bone has a relatively smaller 
antero-posterior diameter, the occipital region is more convex, and continued more 
gently and gradually into the upper region of the skull. The zygomatic arch, 
which is unusually slender, is more dilated (especially on the anterior part) 
thus giving a squareness to the general form. The nasal bones are not so much 
attenuated posteriorly. The length of the skull is 8| lines, the greatest width is 
lines, and the distance between the outer side of the incisors and the front 
molar is 2| lines. 
The dentition is figured in Plate 34, figs. 4. b and 4. c. 
“This specimen was given me by Mr. Bynoe, the surgeon of the Beagle, who 
caught it amongst some long dry grass.” — D. 
MUS FLAVESCENS. 
Plate XIII 
Mus flavescens, Waterh., Proceedings of the Zoological Society of London, for February 1837, p. 19 . 
M. supra colore cinnamomeo , lateribus capitis, corporisque, cequb ac pectore, auratis ; 
gula abdomineque jlavescenti-albis : pedibus sordide albis : auribus mediocribus 
rotundatis, pilis Jlavis obsitis : caadd, corpore, capiteque longiore, supra fused, subtus 
sordide alba : tarsis longis. 
Description. — Fur long and moderately soft ; general colour of the upper parts 
bright brownish yellow ; on the sides of the head and body bright yellow ; 
towards the rump of a deeper hue, and inclining to orange ; under parts pale 
yellow, or yellow-white ; chest yellow. The fur both of the upper and under 
parts of the body deep plumbeous at the base. Feet flesh colour, covered 
above with white hairs : tarsi long, naked beneath. Ears small, tolerably 
well clothed with hairs ; those on the inner side yellow, but many of them 
blackish at the base ; on the outer side, the hairs are blackish on the fore part 
and yellow on the hinder part. The hairs of the ordinary fur of the back are 
of a deep rich yellow colour at the tip, and the longer hairs are blackish. 
The tail is long, deep brown above and whitish beneath ; the hairs of the 
