MICROTUS 687 



paler, less buft'y and less unifonii ; skull larger and heavier, the 

 brain-case deeper than in the typical form. 



Colour. — Upper parts paler than in unfaded specimens of 

 true arvalis, the tips of hairs of underf ur a dull cream-buff against 

 which the black tips of long hairs are rather noticeably con- 

 trasted, producing an evident effect of grizzling seldom approached 

 in the typical form. Underparts a light grey (about Ridgway's 

 No. 10), dulled by the appearance at surface of slaty under-colour, 

 and occasionally (much less often than in true arvalis) washed 

 with light buff". Feet hair-brown occasionally with a buffy tinge. 

 Tail obscurely bicolor, dark brownish above, dull white below. 



Shill and teeth. — The skull differs from that of 31. arvalis 

 arvalis in its general greater size and more robust form, the 

 latter peculiarity often more noticeable in the rostrum than 

 elsewhere ; brain-case essentially like that of true arvalis when 

 viewed from above, the lateral ridges well developed in fully 

 adult individuals, its depth decidedly greater than in the typical 

 form ; auditory bull?e large and well inflated. Teeth showing no 

 special peculiarities. 



Measurements. — Average and extremes of ten adults from the 

 neighbourhood of Tenkitten, Ostpreussen, Germany : head and 

 body, 111-3(105-120); tail, 35-5(31-41); hind foot, 17-5 (17- 

 18-6). For cranial measurements see Table, p. 689. 



Specimens examined. — Sixty, from the following localities on or near 

 the Baltic coast of East Prussia : near Konigsherg, 1 (U.S.N.M.) ; Ten- 

 kitten, 40 (U.S.N.M.); Frische Haff, 2 (U.S.N.M.); Sauglienen, 4 

 (U.S.N.M.); Legehnen, 4 (U.S.N.M.); Lochstedt, 4 (U.S.N.M.); Baltic 

 coast, 5 (U.S.N.M.). 



BemarJcs. — This race is readily distinguishable from the other 

 European forms of Microtus arvalis by its large size, grizzled 

 greyish colour, and robust, strongly angled skull. So far as at 

 present known it is confined to the coast i-egion of extreme 

 eastern Germany. 



Microtus arvalis levis Miller. 



1908. Microtus levis Miller, Ann. and Mag. Nat. Hist., 8th ser., j, p. 197, 



February, 1908. Type in British Museum. 

 1910. Microtus levis Trouessart, Faune IMamm. d'Europe, p. 182. 



Type locality. — Gageni, Prahova, Roumania (at foot of 

 Carpathians, north-west of Bucharest). 



Geographical distribution. — Roumania, southern Hungary and 

 north-eastern Italy ; limits of range not known. 



Diagnosis. — Size and external appearance essentially as in 

 M. arvalis duplicatus ; skull narrow and rounded, the interorbital 

 region not developing a distinct ridge until late in life ; brain-case 

 long and narrow, its length measured from interorbital constric- 

 tion to condyle greater than zygomatic breadth. 



