MURID^E 



473 



in the Pleistocene of the Altai, while an extinct one has been 

 described from the Pliocene of North China. 



Subfamily Deomyinse. Represented only by the under- 

 mentioned genus, in which the bituberculate anterior and tricusp- 

 idate middle ridge of the first upper molar presents a condition 

 intermediate between that obtaining in the Cricetince and that of 

 the Murince. 



Deomys. 1 Externally as in Mus. Pollex with a narrow nail ; 

 hind feet elongate. Infraorbital vacuity of skull triangular, not 

 narrowed below. Upper incisors with a pair of minute grooves. 

 First upper molar with seven distinct tubercles, of which three are 

 placed on the middle ridge, and two on each of the others. One 

 species, D. ferrugineus, from the Lower Congo, an animal about the 

 size of the Common Mouse. 



Subfamily Murinse. Molars rooted and tuberculated ; those 

 of the upper jaw with three longitudinal rows of tubercles (Fig. 

 206, A). 



This group includes the true Rats and Mice, and may be 

 regarded as more 

 specialised than 

 the Cricetince. 

 All the members 

 of the group 

 closely resemble 

 one another, and 

 are light and 

 active, with large 

 ears, bright eyes, 

 and long and 

 scaly tails. Their 

 coloration, in 

 conformity with 

 the fossorial and 

 nocturnal habits 

 of most of the 

 forms, is sombre, 

 and their move- 

 ments are re- 

 markably agile 

 and graceful. 



Mus. 2 Incisors 

 narrow, without 



grooves. Structure of molars as in Fig. 206, A (p. 463). Incisive 

 foramina of skull long ; coronoid process of mandible well developed. 



1 0. Thomas, Proc. Zool. Soc. 1888, p. 130. 

 2 Linn. Syst. Nat. 12th ed. vol. i. p. 79 (1766). 



Fio. 211. The Australian Brown-footed Rat (Mus fitscipes). 

 After Gould. 



