738 RODENTIA 



ARVICOLA TERRESTRIS LinnSBUS. 



1758. [Mus] terrestris Linneeus, Syst. Nat. i, 10th ed., p. 61 (Sweden). 



1771. [Mus] paludosus Linnaeus, Mantissa Plantarum, pt. 2, p. 522 

 (Sweden). 



1827. [Hypudseus terrestris] $ ater Billberg, Synopsis Faunae Scandinaviae, 

 p. 4 (Gottland, Sweden). 



1827. [Hypud&us paludosus] littoralis Billberg, Synopsis Faunae Scandi- 

 naviae, p. 5 (Smaland, Sweden). 



1827. [Hypudseus paludosus] y aquaticus Billberg, Synopsis Faunae Scandi- 

 naviae, p. 5 (South Sweden). 



1858. Arvicola amphibius. a. Blasius, Saugethiere Deutsohlands, p. 344 

 (part). 



1910. Arvicola terrestris Miller, Proo. Biol. Soc, Washington, xxiii, p. 20, 



March 23, 1910. 

 1910. Arvicola terrestris Trouessart, Faune Mamm. d'Europe, p. x. 



Type locality. — Upsala, Sweden. 



Geographical distribution. — Scandinavian Peninsula, eastward 

 into Finland ; limits of range not known. 



Diagnosis. — Size less than in Arvicola amphibius, but general 

 proportions not peculiar (head and body about 175 mm., tail 

 about 100 mm., hind foot usually 28 to 31 mm., condylobasal 

 length of adult skulls, 36 to 39 mm.) ; colour dark, essentially as 

 in A. amphibius, but cheeks usually more yellowish than surround- 

 ing parts ; skull slightly but evidently fossorial in form, the 

 rostrum and occiput tending to be obliquely truncate, the upper 

 incisors noticeably projecting forward ; interparietal tending to 

 be sub-quadrate in outline ; teeth rather heavy, but roots of m 1 

 and m 2 never forming protuberances on lower surface of mandible ; 

 habits both aquatic and mole-like. 



External characters. — Aside from the somewhat less robust 

 general form correlated with the animal's smaller size there 

 appear to be no tangible external characters to distinguish 

 Arvicola terrestris from A. amphibius. 



Colour. — Upper parts varying from broccoli-brown to mars- 

 brown, heavily overlaid with black, the latter usually though 

 not always in excess and producing a general effect not far from 

 seal-brown, especially along median dorsal region ; underparts a 

 distinctly rusty ochraceous-buff, in some specimens almost tawny, 

 everywhere dulled by the slaty under-colour, and fading on throat 

 to an indefinite yellowish grey; cheeks and sides of head, 

 frequently to and including ears, tinged with rusty like that of 

 underparts, the suffusion usually producing a decided contrast 

 with surrounding parts ; feet varying from hair-brown to a deep 

 blackish brown ; tail blackish throughout, the under surface often 

 sprinkled with greyish hairs. 



Skull. — The skull is not so large as that of Arvicola amphibius 

 or A. sapidus. In form it differs from the skulls of the strictly 

 aquatic members of the genus in a decided tendency to assume a 



