88 Bailey New Species and Subspecies of Voles. 



General characters. Like nanus but paler, clearer gray; skull with 

 larger bullte and greater mastoid breadth ; zygomatic arches less widely 

 spreading; upper incisors bent more abruptly downward. Hip glands 

 conspicuous in adult males. 



Color. /Summer pelage : Above, clear dark grayish, formed by pale buffy 

 and black tipped hairs ; sides shading to lighter gray and belly to white; 

 feet dark gray; tail bicolor, grayish below ; blackish above. 



Cranial characters. Skull slightly narrower and more elongate than in 

 nanus ; interparietal averaging longer ; bullae decidedly larger and fuller ; 

 mastoid breadth relatively greater; incisors scarcely reaching beyond 

 nasals ; molar pattern as in nanus. 



Measurements. Type: Total length 149 ; tail vertebrae 42 ; hind foot 20. 

 Skull of type : Occipital condyle to anterior base of molars 17.4; posterior 

 tip of nasals to foramen magnum 19.2; zygomatic breadth 15; mastoid 

 breadth 12.3 ; alveolar length of upper molar series 6.3. 



Microtus montanus arizonensis subsp. nov. 



Type from Springerville, Arizona. No. fHt> c? ad -> U. S. Nat. Mus., 

 Biological Survey Coll. Collected Nov. 7, 1890, by E. W. Nelson. Orig. 

 No. 153. 



General characters. Similar to M. montanus, but brighter and more fer 

 ruginous ; lateral pits of palate shallower. 



Color. October and November pelage: Above, yellowish or rusty 

 brown; belly washed with white; feet dark grayish; tail bicolor, gray 

 ish below; blackish above ; lips whitish. Slightly immature specimens 

 are a little duller in color than adults. 



Cranial characters. Skull very similar to that of montanus, but easily 

 distinguished toy the natter palate with shallower lateral pits, and by 

 thicker pterygoids ; condyloid process of mandible slightly shorter ; 

 dentition not different. 



Measurements. Type : Total length 184 ; tail vertebrae 55 ; hind foot 20. 

 Average of 7 specimens from type locality : Total length 158 ; tail verte 

 bra 41 ; hind foot 20.6. Skull of type : Basal length 27.3 ; nasals 8 ; zygo 

 matic breadth 16; mastoid breadth 12.2; alveolar length of upper molar 

 series 6.5. 



Microtus pennsylvanicus labradoiius subsp. nov. 



l\/pefrom Ft. Chimo, Ungava, Labrador. No. |ff, 9 ad., Merriam 

 Coll. Collected Nov. 15, 1882, by L. M. Turner. 



General characters. Size and proportions approximately as in Microtus 

 drummondi. Skull natter with much smaller audital bullae and more 

 protruding upper incisors. 



Color. (Much changed by alcohol) : Above, dark brownish ; belly 

 whitish ; tail bicolor ; feet pale. 



Cranial characters. Skull flattened, not much ridged or angled ; post- 

 orbital ridge prominent; nasals short, cuneate, and scarcely reaching 



