482 MURID^— ARVICOLA 



1845. Arvicola amphibius, sub-var. nigricans, E. de Selys-Longchamps, Atti 

 della Sesta Riunione degli Scienziati Italiani (Milan), 1844, 322 ; without descrip- 

 tion, hence a nomen nudum. 



1S57. Arvicola amphibius (a.) J. H. Blasius, Siiugethiere Deutscklands, 344 (part). 



1895. MiCROTUS AMPHIBIUS, Richard Lydekker, Hand-book to the British Mammalia, 

 iiii ; Aflalo ; Johnston. 



1905. Arvicola amphibius, J. G. Millais, Mammals of Great Britain and Ireland, 

 ii., 287 ; Pycraft, British Museum Guide to the British Vertebrates, 1910, 8 and 81. 



1910. Arvicola amphibius amphibius, G. S. Miller, junr., Proc. Biol. Soc. Wash., 

 xxiii., 19, 23rd March, and Cat. Mamm. Western Europe, 1912, 730. 



1910. Arvicola terrestris amphibius (part), E. L. Trouessart, Conspectus 

 Mammalium Europa, 194. 



The synonymy is that of the species and typical sub-species 

 amphibius ; that of the black sub-species reta is given in the article on 

 that animal. The British Water Rat is undoubtedly the Mus amphibius 

 of Linnaeus, who adopted it from Ray's Mus major aquaticus of England. 

 He states that it is a species not closely examined by himself, and 

 perhaps not really distinct from his Mus terrestris, under which name 

 he had just previously lumped all the other European water rats. 

 Misled by Ray he described it as plantis palmaiis, i.e., with the hind 

 feet webbed, which led Gilbert White (letter x. to Pennant, 4th August 

 1767) to comment on the description, which he found, but for the 

 webbed feet, applied exactly to a rat which he had himself discovered 

 on the banks of " our little stream." 



Distribution: — This is the Common Water Rat of England and 

 southern Scotland, where it is numerous in suitable localities throughout 

 the mainland, and occurs in the Isle of Wight and Anglesey. It ascends 

 to 800 or 1000 feet in Wales (Forrest) ; and in Dumfriesshire, in May 

 1887, W. Evans saw a buzzard catch one on the hills above Loch Skene, 

 at an elevation of about 2000 feet. Somewhere north of the water- 

 sheds of the Clyde and Tay (H. A. Macpherson and Aplin, Zoologist, 

 1892, 281-293), it gives way to the northern sub-species reta, but no 

 exact details are available. There are black colonies in Norfolk and 

 Cambridgeshire, the status of which is not known. 



Description :— This is a large Water Rat, with hind foot reaching 

 32-35 mm., and condylo-basal length of skull 42 mm. or more in adults. 

 The colour is moderately dark, black rarely replacing brown on the 

 upper surface, and melanistic specimens are comparatively rare. 



Exceptional variations are comparatively frequent, and there are 

 a good many records of partial or complete albinos, as well as of pied 

 (see Service, Ann. Scott. Nat. Hist., 1896, 206), grey, and reddish sandy 

 individuals. As is usual in such cases, the tendency to variation in a 

 particular direction seems to be inherited, and more than one white or 

 whitish individual may be observed in the same locality at or about 

 the same time. 



