88 MILLER 



Synopsis of the Redbacked Mice of Europe. 



Skull strongly angular as in Microtus^ the postorbital processes well 

 developed ; teeth large, rooted late in life, the maxillary molar row 

 about as long as diastema; posterior lower molar distinctly encap- 

 suled ; red area of back very strongly contrasted with clear gray 



sides (subgenus Craseottiys) f Evotomys rufocanus 



Skull much less angular than in Microtus^ the postorbital processes 

 obsolete or very small ; teeth small, rooted early in life, the 

 maxillary molar row conspicuously shorter than diastema ; pos- 

 terior lower molar not encapsuled; red area of back not very 

 sharply contrasted with yellowish gray of sides (subgenus 

 Evotomys'). 

 Tail densely furred, forming about 30 percent of total length, 

 its pencil at least one-fourth as long as caudal vertebrae. 



Evotomys rutilus 

 Tail sparsely furred, forming about 33 percent of total length, 

 its pencil never more than one-sixth as long as caudal verte- 

 brcE. 

 Greatest length of skull about 36 mm. ; hind foot 30 (iS) or 

 more. 

 Ratio of tail vertebrae to total length 35 to 3S ; skull 

 broad and rounded, the zygomata light, generally con- 

 vergent anteriorly and never abruptly flaring. 



Evotomys nageri 

 Ratio of tail vertebrce to total length 32 to 36 ; skull nar- 

 row and ridged, the zygomata heavy, abruptly 

 flaring anteriorly and generally convergent poste- 

 riorly. 

 Nasals narrow (greatest width of both together dis- 

 tinctly less than half length) ; ratio of tail verte- 

 brae to total length generally 34 to 36. 



Evotomys norvegicus 



Nasals broad (greatest width of both together about 



half length) ; ratio of tail vertebrae to total length 



about 33 Evotomys vasconi^ 



Greatest length of skull about 34 mm. ; hind foot 20 (iS) or 

 less Evotomys hercynicus 



