VII.] RODENTIA. 239 



comys, Steatomys, and Lophuromys, the last having the fur replaced 

 by fine flattened bristles. Although there is no palaeontological 

 history of either of the preceding sub-families, the Cricetince have 

 already been shown to date from the lower Oligocene of Europe. 

 Their sole Ethiopian representative is the single species of the 

 genus Trilophomys^, from Upper Nubia and the Red Sea littoral 

 in the neighbourhood of Suakin, and perhaps ranging into southern 

 Arabia. The crested rat, as the creature is called, takes its name 

 from the prominent crest of stiff hair running down the back ; 

 while it is specially characterised by the roofing over of the whole 

 upper surface of the skull with bone, on which account it has 

 (quite unnecessarily) been made the type of a family by itself. 

 Perhaps, however, the most interesting member of the family 

 inhabiting Ethiopia is a species of mouse known as Deomys, repre- 

 senting both a genus and sub-family by itself, and characterised by 

 having its upper molars intermediate between those of the crice- 

 tines and murines. Doubtless, therefore, this rodent is a somewhat 

 modified descendant of the true cricetines which entered Africa 

 while it was still united to Madagascar; its habitat being that 

 refuge for ancient types, the lower Congo valley. The two other 

 generic representatives of the family, Cricetomys and Saccostomus, 

 although resembling the hamsters in the presence of cheek- 

 pouches, have molars like other Murina, and are accordingly 

 referred to that sub-family. While there are two species of the 

 second genus, there is but one of the first. By some zoologists 

 the striped mice, as typically represented by the Barbary mouse, 

 are separated from Mus to form a genus Arvicanthis* , which is 

 mainly Ethiopian. 



The small family of the Spalacidce, or burrowing-rats, has four 

 genera out of six exclusively Ethiopian, while a fifth (Rhizomys\ 

 which is mainly Oriental, enters Abyssinia. Of the four Ethiopian 

 genera, which constitute a sub-family by themselves, Bathyergus 

 includes only the great Cape mole-rat of South Africa; and 

 Myoscalops has also but a single species, although there are several 

 of Georhychus. Closely allied to the latter are two tiny little 

 burrowing and nearly naked creatures (Heterocephalus) from 



1 Syn. Lophiomys. '* Syn. Isomys. 



