472 THE BROWN RAT AND THE BLACK RAT CHAP. 
frequents barns, and is thus sometimes mistaken for the Common 
Mouse, from which, however, it is to be distinguished by its 
coloration and longer ears. The latter, JZ musculus, is too 
familiar to need much description. A curious variety of it has 
occurred. This has a thickened and a folded skin lke that of 
a Rhinoceros, and the hair has disappeared. The Black Rat, 
M. rattus, is like a large Mouse, and is smaller and blacker in 
colour than the “ Hanoverian Rat.” It is sometimes called the 
“Qld English Rat,’ but seems nevertheless to be not a truly 
indigenous Rodent. It has been so defeated by competition with 
the Hanoverian Rat that it is now not a common species in this 
country. 
The Hanoverian or Brown Rat, JZ decumanus, is a larger and 
a browner animal than the last. It is very widely distributed 
through the globe, no doubt largely on account of the fact 
that it is readily transported by man. The same is the case 
with the Common Mouse, whose real origin must be a matter of 
doubt. The original home of the Brown Rat is thought by 
Dr. Blanford to be Mongolia. There is so far a justification 
for the name “Hanoverian Rat” that the animal seems to 
have reached this country about the year 1728. But there 
is no reason for calling it, as is sometimes done, the Norway 
nat. 
Some members of this genus, whose fur is interspersed with 
spines, or which are quite spiny, have been separated as a genus, 
Leggada, which, however, is not generally allowed. 
Closely allied again is Chiruromys, which has a_ strongly 
prehensile tail, a feature which is not common among the 
Myomorpha, though Dendromys, a tree-frequenting form, and 
Mus minutus, already spoken of, show the same character. 
Many Mice seem to have prehensile tails, which they can curl 
round branches ; but it is not so fully developed as in the species 
just named. 
A ntimber of other genera are referable to the true Mice, the 
sub-family Murinae of Thomas’s classification. The Syrian and 
African Acomys has very spiny fur, so much so that “when 
it has its spines erected it is almost indistinguishable at 
the first glance from a diminutive hedgehog.” The genera 
Cricetomys, Malacomys, Lophuromys, Saccostomus, Dasymys are 
restricted to the Ethiopian region. Vesokia is Oriental, reaching 
ad ew. 
