THE FIELD MOUSE 



511 



naked except in the region of the heel, and it is provided with six 

 normally placed pads; the latter though well developed are smaller 

 than those of the palm ; they are ovate in form, the postero-external 

 being the smallest ; the skin between the pads is finely tuberculo- 

 reticulate, smooth between the last pad and the heel, in which 

 latter situation it is wrinkled. There are six mammae in the female, 

 one pair being pectoral, the remaining ' two pairs inguinal. In young 

 males the glans Jienis is complex; the parts caAled />apil/a centra/is, J>p. 

 laterales, and p. lingualis by Tullberg being distinct, as in Cricetus ; in 

 the adult certain of these elements fuse together, and the glans acquires 

 a simpler form approaching that of higher Murince, e.g. Epimys (see 

 Hinton, Ann. and Mag. Nat. Hist, July 1914, 133). Each testis when 

 fully developed is as large as, or larger than, the brain. 



Pelage : — The fur is soft and never becomes spinous, for though 

 many of the hairs of the back are grooved bristles these are quite weak. 

 The density and length of the fur varies according to the sub-species, 

 age, or season. In English specimens the longer hairs of the back 

 attain a length of about 9 mm. in summer, and 10 mm. in winter. 

 Colour {^A. s. sylvaticus) : — The basal two-thirds of all hairs, at all 

 ages and seasons, are slate-grey ; this tint is concealed by the differently 

 coloured hair tips. The general colour of the back in adults in fresh 

 pelage is "wood-brown," with a more or less distinct reddish tinge 

 posteriorly, and becoming paler or more bufify on the head, shoulders, 

 and flanks. Numerous long black hairs slightly but distinctly cloud 

 the middle of the back with black ; on the flanks, where they are fewer, 

 these hairs produce a well-marked "lining" effect. On the cheeks, 

 sides of the neck, outer surfaces of the fore legs, and along a narrow, ill- 

 defined region immediately above the line of demarcation on each side, 

 the colour is a dull light buff. The line of demarcation is always distinct 

 in adults. The whole ventral surface and the dorsal surfaces of the 

 feet are of a dull white or silvery hue, irregularly darkened on the throat 

 and belly by the slaty bases of the hairs, and sometimes washed with 

 buff. A more or less bright spot of buffer orange is frequently present 

 on the throat in well-developed specimens ; sometimes this forms a 

 complete collar, or is lengthened into a feeble median stripe; it is 

 often quite minute or wholly absent. The ear is dull brown, with 

 lighter or occasionally silvery edges. The tail is inconspicuously 

 bicoloured, its upper surface being dark brown, whitish below. 



Moult : — Specimens showing the moult are rare, and the change of 

 coat is probably made in a gradual and inconspicuous manner (Barrett- 

 Hamilton, Proc. Zool. Soc, 1900, 399). Adams has seen only one case 

 in which the line of demarcation was in moult ; this, a young female 

 (H. and B., 73 mm. ; perforate) taken at Reigate in June, had the hinder 

 and central part of the ventral surface ,in the first or grey pelage, while 

 laterally and forwards the thick white adult pelage was developed. A 



