472 THE BROWN RAT AND THE BLACK RAT chap. 



frequents barns, and is thus sometimes mistaken for the Common 

 ]\Iouse, from wliich, however, it is to be distinguished by its 

 coloration and longer ears. The latter, if. musculus, is too 

 familiar to need much description. A curious variety of it has 

 occurred. This has a thickened and a folded skin like that of 

 a Ehinoceros, and the hair has disappeared. The Black Eat, 

 jr. rattus, is like a large Mouse, and is smaller and blacker in 

 colour than the " Hanoverian Eat." It is sometimes called the 

 " Old English Eat,'' but seems nevertheless to be not a truly 

 indigenous Eodent. It has been so defeated by competition with 

 the Hanoverian Eat that it is now not a common species in this 

 country. 



The Hanoverian or Brown Eat, M. 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 ]\Iouse, whose real origin must be a matter of 

 doubt. The original home of the Brown Eat is thought by 

 Dr. Blanford to be Mongolia. There is so far a justification 

 for the name " Hanoverian Eat " 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 ]\^orway 

 Eat. 



Some members of this genus, whose fur is interspersed with 

 spines, or which are quite spiny, have been separated as a genus, 

 Lrggada, which, however, is not generally allowed. 



Closely allied again is Ghiricromys, which has a strongly 

 prehensile tail, a feature which is not common among the 

 Myomorpha, though Dendromys, a tree - frequenting form, and 

 JFiis minutus, already spoken of, show the same character. 

 ]\Iany 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 number of other genera are referable to the true ]\lice, 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, 3Ialacomys, Loipliuromys, Saccostomus, Basymys are 

 restricted to the Ethiopian region. JVcso/iia is Oriental, reaching 



