ARVICOLA 401 



Type. — Unknown ; species based upon the Mus major aquati- 

 cus of Ray, >Syn. Anini. Quadr., 1693, p. 217. 



I'ype locality. — England. 



Range. — England, Wales, and Southern Scotland; exact 

 northern limits of range unknown. Found also in the Isle of 

 Wight and Anglesey. 



Characters. — Size large, hind-foot commonly between 32 and 

 35 mm., condylo-basal length 42 mm. or more in adults. Colour 

 moderately dark, black rarely replacing brown upon the upper 

 surface. Melanistic specimens comparatively rare. 



For external and cranial dimensions, see tables at end of 

 volume. 



5h. Arvicola amphibius reta Miller. 



1832. Arvicola aler Macglllivray, Mem. Wernerian N.H.S., 6, p. 429; 



preoccupied by Ilijpudceus lerrestris, p, ater of Billberg, 827 



[= Arvicola terrestris], 

 1835. Arvicola amphibia, var. p, A. ater Jenyus, Mam. Brit. Vert. 



An., p. 33. 

 1910. Arvicola amphibius reta Miller, Proc. Biol. Soc. Washington, 23, 



p. 19; Catal. Mamm. W. Europe, 1912, p. 732; Barrett-Hamilton, 



Hist. Brit. Mamm., 2, 1914, p. 483. 



Type.—X^rikiiovfn. 



Type locality. — Aberdeen, Scotland. 



Range. — Scotland, except southern portion ; limits of distri- 

 bution not known. 



Characters. — Slightly smaller than in A. a. amphibius, hind-foot 

 usually between 30 and 32 mm., condylo-basal length in adults 

 usually less than 42 mm. Colour darker, black often replacing 

 brown upon the upper surface. Melanistic specimens are frequent, 

 but black and brown individuals may occur in the same litter. 



For external and cranial dimensions, see tables at end of 

 volume. 



6. Arvicola sapidus Miller. 



(Synonymy under subspecies.) 



Range. — Iberian Peninsula and Southern France eastwards 

 nearly to the Italian border ; northern limit of range unknown, 

 but probably extending at least to the neighbourhood of Paris. 



Characters. — General size and outward appearance as in A. 

 amphibius. Skidl distinguished usually by its broader nasals, 

 which at their anterior expansions are together nearly as wide as 

 the rostrum; anterior palatal foramina distinctly larger; audi- 

 tory bidla' larger, and more conspicuously inflated. 



Geographical differentiation. — Two subspecies are at present 

 recognized, viz., the typical and lighter-coloured form inhabiting 

 the greater part of Spain and a darker form inhabiting the 

 Pyrenees and Altantic coast region of South-western France. 



Remarks. — A. sapidus is very closely related to A. amphibius, 



