278 
THE MAMMALS OF EGYPT. 
mm. 
Snout to vent... 64 
Vent to tip of tail. 54 
Length of hind footj without claw. 13'5 
„ „ with claw. 15 
Height of ear^ external meatus. 7 
This is unquestionably M. musculus. 
[Measurements taken from specimens preserved in alcohol. 
Beltim. Eayum. Cairo. Wadi Haifa. 
Head and body. . . 74 74 75 72 80 77 
Tail. 64 60 71 69 81 69 
Hind foot .... 16 15-5 18 17-5 16 17 
Ear. 11-5 12 12 12-5 12 11-5 
The House-Mouse is subject to the same amount of environmental variation as the 
Black Rat {M. rattus), and is almost as widely distributed over the world. 
As a rule, mice that live in towns have dark under sides, while those that live in 
the fields are pale orange or whitish beneath, the base of the fur being still grey. In 
Nubia, the Sudan, and in many parts of Asia a still further development takes place, 
the upper parts being nearly uniform brownish yellow, and the whole of the under parts 
pure white, with the fur white to the base. 
Of the specimens enumerated above, the one from Cairo is a dark-bellied typical 
M. musculus, Linn.; those from Beltim, Gizeh, Fayum, and Suakin are of the yellowish- 
or whitish-bellied race, M. orientalis, Cretzschm.; while those from Wadi Llalfa 
and Fergunt are the pure white-bellied race, M. gentilis, Brants, which is found 
throughout the Sudan [Mus pallescens, Fleugl.). Some twenty or more names have 
been given to this mouse from different parts of the world, the most commonly 
used, and the only ones likely to have been applied in literature to examples 
from Egypt, are Mus ])rcetcxtus, Brants, Mus bactrianus, Blyth, and Mus spretus, 
Lataste.— AV. E. de AV.] 
