92 MILLER 



Belly dirty white or cream color, darkened by the plumbeous bases of 

 the hairs which show through irregularly at the surface. Feet whit- 

 ish. Ears like dorsal stripe. Tail sharply bicolor, brownish tinged 

 with red above, dirty white below. Fur everywhere slaty plumbeous 

 at base. 



Individual variation among adult skins is too inappreciable to need 

 special comment. I have seen no immature specimens. 



Skull. — The skull of Evotomys riitilus is small, smooth, and 

 rounded, in general appearance hardly distinguishable from that of 

 E. hercyniciis. The zygomata are rather abruptly though not very 

 widely flaring anteriorly, so that in the malar region the two arches 

 are parallel with each other and with the main axis of the skull. 

 Rostral protuberances small but well developed and standing out con- 

 spicuously in front of zygomatic processes of maxillaries. Lateral 

 outline of nasals nearly straight from base to tip. Posteriorly the 

 nasals extend slightly beyond nasal branches of premaxillaries. They 

 are squarely truncate. Fostorbital processes essentially obsolete. 

 Braincase low and flat (the skull distinguishable by this character 

 alone from that of any of the members of the hercynicus group), 

 subrectangular in outline when viewed from above. Palate normal 

 except that the foramina immediately in front of lateral bridges are so 

 large and numerous that the bridges are generally somewhat en- 

 croached upon and rendered imperfect. Audital bullae as in E. her- 

 cynicics^ therefore slightly smaller than in Microtus agrestis and 

 much smaller than in Evotomys rtifocaniis . 



Measurements of an adult skull from Lapland : Greatest length 24; 

 basal length 32.4; basilar length 20.6; zygomatic breadth 13; mastoid 

 breadth 11.8; interorbital constriction 4; nasals 7 ; incisive foramen 

 5; diastema 7.4; palatal length 10. S; occipital depth (in median line) 

 7; frontopalatal depth (at middle of molar series) 6; mandible 13. 8; 

 maxillary toothrow (alveoli) 5; mandibular toothrow (alveoli), 5. 



Teeth. — The teeth of Evotoj)7ys riitilus present no characters of 

 special importance. Relatively to the size of the skull they are pro- 

 portioned as in E. hercynictis. I can see no tangible specific charac- 

 ters in the enamel pattern. 



Measurements. — Two specimens from northern Sweden measure 

 respectively : Tail vertebras 34 and 39 ; pencil 1 1 and 9 ; hind foot 

 with claws iS and 1S.4; hind foot without claws 17. 



Specimens cxaynined. — Five, from the following localities : Norway : 

 South Varanger, Finmark, 2. Sweden: Karesuando, i ; Lapland, 2. 



Rejuarks. — This arctic species is instantly recognizable by its small 



