The American Voles of the Genus Evotomys. 119 



Color.— Winter pelage : dorsal stripe well defined, extending from in front 

 of ear^^ to rump, lich rufous or ferruginous, slightly darkened with black 

 tipped liuirs ; face, sides, and rump bright buff\' oehraceous : belly heavily 

 wusiied with buff or rich cream ; feet white ; ears rufous like back ; tail 

 sharply bicolor, buff or ochraceous buff below, above brownish at base, 

 blackish along terminal portion. Summer pelage: dorsal stripe darker; 

 sides less strongly huffy ; belly soiled whitish ; feet gray ; tail less sharply 

 bicolor. 



Cranial characters. — Skull thick and strong, not much ridged or angu- 

 lated ; upper outline slightly arched, not concave interorbitally ; brain 

 case squarish ; ascending arm of premaxilla terminating on a line with 

 truncate end of nasals ; audital bulUe moderately large and inflated, hid- 

 ing ends of pterj'goids in side profile ; posterior edge of palate slightly 

 notched ; lateral bridges wanting, so that instead of a shelf the bone stands 

 out as a tongue ; * molars not peculiar ; incisons stout, with orange colored 

 enamel surface. 



Measurements. — In the original description Pallas gives the following 

 measurements: " Xose to anus, 3^^ 7^^^ [=98 mm.]; tail vertebrae, 1^^ 

 V [=29 mm.]; pencil, 3''' [= 7 mm.] ; hind foot, SV [18 mm.]." 

 Two specimens from Finmark and Sweden measure in the dry skin : tail, 

 with vertebrae left in, 24; hind foot, 20. An alcoholic specimen from St. 

 Michaels, Alaska: total length, loO; tail vertebrae, 30; hind foot, 20. 

 Skull of adult (No. 6555, Merriam collection) from Finmark : basal length, 

 23.5; nasals, 7.8; zygomatic breadth, 14.3; mastoid breadth, 12 ; alveolar 

 lengtii of upper molar series, 5. 



General remarks. — The above description is based on four specimens in 

 the JMerriam collection from Lapland and Finmark, which are assumed 

 to be typical rutilus. The American form is similar in most details, but, 

 as all of the available skins are in wretched condition and without reli- 

 able measurements, a satisfactory comparison is impossible. 



The side glands do not show in any of the four European specimens, 

 though one is marked (J' and two are unmarked for sex. A faint trace 

 of them may be seen in two of the specimens from St. Michaels, Alaska. 



In the original description Pallas states that Eroionujs rutilus inhabits 

 the woods locally, but is also found in the cold Arctic regions as far north 

 as the Gulf of Obi. In Arctic America it has been taken at various 

 places on the Barren Grounds to as far north as Fort Andei'son, as well as 

 at the edge of timber. As yet too little is known of its range to safely 

 attribute it to the Barren Grounds, where it probably belongs. 



Specimem e.mmined.— Total number, 27; 23 in U. S. Nat. Mus.; 4 from 

 Europe, in Merriam collection. 



Ala.^ku: St. ^Michaels, 17; Kagiktowik, 2; Fort Yukon, 2. 

 Northwest Territory: Fort Anderson, 1; Fort Simpson, 1. 



*In Alaska specimens the lateral bridges are usually complete. This 

 and other slight differences may separate the American from the Old 

 World form of rutilus when series of good specimens of the two can be 

 brought together. 



