1900.] MUS SYLVATICDS AND ITS ALLIES. 419 



The slcull is narrower and slightly smaller than that of adult 

 of the subspecies intermedins, reaching a length of only about 

 25 mm., and having the anterior portions of the frontals more 

 attenuated, and the nasal region proportiouately more slender 

 than in the latter subspecies. 



Distribution. At present known only from the typical series. 



General Remarks. The Mice identified by Mr. Oldfield Thomas 

 as M. chevrieri form quite a nice series of eleven specimens, with 

 which may be considered eight specimens collected by Mr. C. B. 

 Rickett in the same locality. Although obviously representing a 

 subspecies of M. sylvaiicu*, I am unable to ideutify them with 

 any known phase of that species. They cannot be 21. chevrieri, 

 for they are not larger, but rather smaller than the average ; 

 and the colour of the upperside, although brighter than that of 

 M. sylvaticus from Western Europe, is not like that of M. confu- 

 cianus. They cannot well be M. s. arianus, Blanford, the description 

 of which certainly does not apply to them, while they differ in 

 more than one obvious respect from M. s. intermedins. 



The series represents individuals of very varied age, from quite 

 young specimens to adults. The young seem to undergo very 

 different changes of colour in their progress to maturity from 

 those undergone by M. s. intermedins. When very young, they 

 are of a darker slate-colour ; and they appear to retain the dull 

 slaty hues of immaturity until they reach a considerable, perhaps 

 their full, size. Thus no. 97.6.6.11, a nursing female, with 

 mammse 1 + 4, is in colour of the upperside very like an ordinary 

 M. musculus, but, unlike this species, has a sharply defined white 

 belly. Another nursing female, no. 98.11.1.22, is in process of 

 losing her immature coat, and presents a three-coloured appearance, 

 having the belly white, the central dorsal region clothed in the 

 dusky immature tints, while the flanks show the red colours of an 

 adult. Another specimen has progressed farther, and shows traces 

 of the dark colour only on the rump. This patchy method of 

 assumption of the adult coat seems to be quite unknown in M. s. 

 intermedins, in which the process seems to be much more gradual : 

 it woidd appear to be highly characteristic of this new subspecies. 

 The white belly is present in specimens of all ages, and two 

 or three show a breast-spot or band of more or less complete 

 development. 



The skulls of this subspecies are interesting, and are remarkable 

 as compared with skulls of M. s. intermedins and even with the 

 skull of the South Shensi specimen, as being very much narrower 

 and more attenuated in the anterior frontal and nasal region. 

 They are far less massive than in examples from lioumania, but 

 almost equal in size those of medium-sized individuals from 

 Western Europe. Xone of those which I have at my disposal 

 are quite perfect, but the respective dimensions of total length 

 and breadth would appear to be about 25 and 11 mm. The 

 tubercles of the molar 1 are rather regularly arranged, and 1 think 

 that the central tubercle of the last row (C" of Hensel) is more 

 prominent than in M. s. intermedins. 



