S64 MURID^— MICROMYS 



bulla, 315 to 34-4; (9) and (10) nasal length and breadth, 29'2 to 

 36 and 8-6 to 11-5 ; (11) palatal length, 50-9 to 54-3 ; (12) diastemata, 

 22-1 to 25-2; (13) incisive foramina, length, iJ-S to 20-6. The 

 dimensions not mentioned here are in substantial agreement with 

 those of the Field Mice. 



The mandible is much like that of the Field Mouse in form, 

 differing, apart from its much smaller size, only in some slight details 

 of the angular and coronoid processes, the former being a little more 

 concave above, the latter a little more recurved. The cheek-teeth 

 (PI. XXVIII., Fig. 7) are described above under the genus. 



Geographical variation : — In addition to M. m. soricinus and 

 minutus (of which last no specimens have been seen), five or six other 

 sub-species are at present recognised. Of these, M. m. pratensis, 

 Ockshay {^Nov. Act. Phys.-Med. Acad. Caes. Leop. Car. Nat. Cur., xv., 2, 

 1 83 1, 243, described from Western Hungary), ranges throughout 

 Hungary into Rumania. In this form, as described by Miller, the 

 posterior half of the body and the outer surfaces of the hind legs are 

 as in soricinus, the head and the anterior half of the body are decidedly 

 greyish, the white under parts receive a bluish tinge from the slaty 

 hair-bases, and the tail is rather sharply bicoloured. In a series 

 collected at Csehtelek, Eastern Hungary, during October and November 

 1913, by Fraulein von Wertheimstein, specimens with unworn or very 

 slightly worn teeth (condylo-basal length from 15-6 to 16-5 mm.) have the 

 coloration as va pratensis, the rufous tint so characteristic of similarly 

 grown British Harvest Mice only appearing towards the rump ; in a 

 female with slightly worn teeth (head and body, 63 ; condylo-basal 

 length, 16-9 mm.) the colour, save for slightly darker flanks, is nearly 

 as bright and rufous as in specimens taken at Colchester in April ; in 

 a fully adult female with half-worn teeth (head and body, 71 ; condylo- 

 basal length, 17-8 mm., B.M. No. 14.1.3.35) the colour is quite as 

 red and bright on the head, back, and flanks as in the brightest 

 English specimens ; the hairs of the belly and chest are pure white 

 to their bases, and on each side between the white belly and the 

 rufous flanks there is a narrow belt of almost pure buff. 



The remaining sub-species are Asiatic. M. in. batarovi, Kastchenko 

 {Ann. Mus. Zool. Acad. Imp. Set., St Petersburg, xv., 1910, 284), from 

 the Transbaikal, is characterised by its short tail, measuring only from 

 60 to 70 per cent, of the length of the head and body ; by its dark back, 

 rufous towards the rump, and its ashy-white belly. Mus minutus, van 

 kytmanovi, Kastchenko {pp. cit.), is described as an intermediate 

 between typical minutus and batarovi. M. m. ussuricus, Barrett- 

 Hamilton {Ann. and Mag. Nat. Hist., April 1899, 344), described from 

 Ussuri, Eastern Siberia, is a dark-backed form with the belly washed 

 with dirty yellow, and no distinct line of demarcation. M. m. pygmceus. 



