THE HOUSE MOUSE 637 
one of the palmar pads in size, and bearing a small flattened nail ; digit 
3 is the longest finger, digit 4 being very slightly shorter; digit 2 is 
slightly shorter than digit 4, and digit 5 reaches a little beyond the 
base of digit 4. The five palmar tubercles are small, occupying less 
than half of the surface of the palm; the three anterior are small and 
round, the external one having a small additional free tubercle by its 
outer side at the base of digit 5 ; the posterior pads are larger and oval. 
Between the pads the skin is irregularly wrinkled and granular ; the 
ventral surfaces of the digits have annular scales which tend to be 
interrupted in the middle. 
The feet compared with those of the Field Mouse are shorter and 
broader, and each has the usual six pads. The latter are relatively 
small, and widely spaced, of oval or rounded form, and differ but little 
from each other in size—the two anterior being slightly the largest, 
the postero-external slightly the smallest. In addition, a little free 
supplementary tubercle is developed to the outer side of the pad at 
the base of digit 5, and there is a similar tubercle to the inner side of 
the pad, at the base of the hallux. The skin between the pads is 
wrinkled, but smooth towards the heel. The hinder part of the sole is 
hairy along the edges, and solitary hairs are scattered between the pads. 
Digits 2, 3, and 4 are the longest, 2 and 4 being slightly shorter than 3; 
digit 5 reaches a little beyond the base of digit 4, and digit 1 extends 
as far as the base of digit 2. Both the fingers and toes (including the 
hallux) are armed with small, simple, curved claws, those of the toes 
being slightly the longer. 
The tail is usually about as long as, or a little longer than, the head 
and body; it is finely annulated with about 180 scaly rings, the 
boundaries of the individual scales being somewhat indefinite; it is 
clothed with numerous short, stiff hairs, each equalling in length the 
width of about two and a half annulations; the hairs do not, however, 
conceal the rings, and they do not form a terminal pencil. 
The fur is soft throughout, longer, and denser on the back ; shorter, 
thinner, and rather closely adpressed on the belly ; grooved bristles 
occur as in the rats, but they are so slender as to produce no sensible 
effect upon the quality of the pelage. The microscopic structure of the 
hair is described below under Pzgientation and Inheritance. 
Colour :—The general colour of the upper parts is a dusky grey, 
irregularly darkened with slate and black along the middle of the back, 
and paling gradually to ashy grey on the flanks and belly. The hairs 
have slaty bases, appearing on the surface in the region of the chin and 
throat, and dusky tips; their subterminal bands are yellow, and these 
produce a more or less well-marked tinge of yellow above and below. 
The ears are of a dull brownish colour, their antero-external edges 
being usually darker than the other parts. The feet are dusky above, 
VOL, II. Disa 
