New Species and Subspecies of Voles. 8^ 



Gem red charactt rs. — Size large ; ears small ; tail rather short ; fur coarse 

 and lax ; colors dark ; hip glands conspicuous in adult males. Skull mas- 

 sive and angular; incisive foramina narrow and closing to a point pos- 

 teriorly. 



( 'olor. — March specimens: Above dark sepia or bister, much obscured by 

 blackish hairs: sides lighter; belly smoky gray; feet dark gray; tail in- 

 distinctly bicolor, blackish above, gray or brownish below; lips usually 

 white; tip of nose in adult usually whitish. Young with a blackish 

 dorsal stripe and dusky feet and tail. 



Cranial characters. — Skull heavy, angular, and much ridged; frontals 

 high; rostrum bent downward ; incisive foramina short, rather narrow 

 and constricted to a point posteriorly; dentition heavy; upper incisors 

 curved abruptly downward; first upper molar with 5 closed triangles; 

 second with 4 triangles in 8 out of 16 specimens; in the other 8, with a 

 slight inner lobe or loop at base of posterior triangle ; third with anterior 

 crescent, three closed triangles and a posterior loop with two inner lobes 

 or horns. 



Measurements.— Typi specimen: Total length 210; tail vertebrae 55 ; hind 

 foot 25.5. Average of 8 specimens from type locality : Total length 17ii : 

 tail vertebra? 47 ; hind foot 23. Skull of type : Basal length 32; nasals 10.2; 

 zygomatic breadth 19.3; mastoid breadth 14.3; alveolar length of upper 

 molar series 8. 



Microtus nevadensis rivularis subsp. now 



Type from St. George, Utah, Xo. -f||f, cj ad., Merriam Coll. Collected 

 Jan. 6, 1889, by Vernon Bailey. Orig. No. 493. 



General characters. — Smaller and lighter colored than its nearest rela- 

 tive, M. nevadensis i skull less rigid and angular; bullae larger ; incisive 

 foramina longer and narrower; ears small, nearly concealed by fur. 



Color. — Winter pelage : Upper parts dull bister, darkened with blackish 

 tipped hairs (similar to californicas) ; sides scarcely paler; belly washed 

 with whitish; feet dull grayish; tail bicolor, grayish below, blackish 

 above. Young darker than adults, but not black backed. 



Cranial characters. — Skull smaller and slenderer than skulls of nevadensis 

 of equal age ; audital bullae much larger and fuller ; anterior end of basi- 

 occipital narrower; incisive foramina narrower and actually as well as 

 relatively longer; angular process of lower jaw longer and slenderer ; in- 

 cisors much slenderer ; molar pattern essentially the same. 



Measurements. — Type: Total length 179; tail vertebrae 48 ; hind foot 23. 

 Stall of type : Basal length 28.2 ; nasals S.'d ; zygomatic breadth 17 ; mas- 

 toid breadth 13.3 ; alveolar length of upper molar series 7.3. 



Microtus nanus canescens subsp. now 



Type from Conconully, Washington. Xo. 90577, $ ad., U. S. Nat. Mus., 

 Biolo-ical Survey Coll. Collected Sept. 12, ls',>7, by J. Alden boring. 

 Orig. Xo. 41 .54. 



