Vol. XXIII, pp. 19-22 March 23, 1910 



PROCEEDINGS 



(IF TIIIC 



BIOLOGICAL SOCIETY OF WASHINGTON 



BRIEF SYNOPSIS OF THE \\^\TERRATS OF EUROPE. 



BY GERRIT S. MILLER, JR. 



The following brief synopsis of the European members of the 

 genus Arvicola is primarily based on studies made in tlic British 

 jNIuseum during the summer of 1908. 



(tknus ARVTCOLA Lacei)i".le. 

 Arvicola amphibius (Liniumis). 



Rize large (head and body about 200 mm., tail about 110 imn., hind 

 foot usually .10 to ;U mm., coudylobasal length of fully adult skulls 40 to 

 44.(1 mm.); tail somewhat more than half as long as head and l)ody; 

 color a])ove dark brown, blackening along back, the sides not decidedly 

 yellowish, the cheeks not contrasted with surrounding parts; skull not 

 fossorial in form, the occiput and rostrum tending to be squarely (verti- 

 cally) truncate, the upj^er incisors not conspicuously projecting; nasals 

 at widest region conspicuously narrower than rostrum ; roots of m j and 

 m 2 forming evident protuberances on lower surface of numdible in old 

 individuals; habits strictly a(iuatic, never mole-like. Confined to (Ireat 

 Britain. 



Arvicola amphibius amphibius (Linnfeus). 



175S. [Mus] amphibius Linnaeus, Syst. Nat., I, 10th ed., p. (H (England: 

 base<l on the 3Itts major aquaticus of Ray). 



Size maximum for the species (hind foot in adults usually o2 to o5 mm. ; 

 coudylobasal length of skull 42 mm. or more) ; color moderately dark, the 

 black rarely in exce.ss of brown on ui)per])arts ; melanism iufrecpient. 

 England and southern Scotland. 



Arvicola amphibius reta nom. nov. 



18o2. Arvicola ater Macgillivray, Mem. Wernerian Soc. Nat. Hist., VI, 

 p. 420. ( Aljerdeen, Scotland). Not IJi/pud;riis terrestri.t jS aler Bill- 

 berg, 1827, a synonym of Arricola terrestris. 

 Size less than in A. arnpliibius a)iiphibii(f< (hind foot usually .">(i to .■i2 



nun., condylol)asal length of skull usually less tlian 42 mm.); normal 



■'i— I'liuc. liioi.. Soc. Wash., XXIH, I'.ilo. (TJ) 



