8<S Balky — New Species and Subspecies of Voles. 



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

 larger bullae 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 huffy 

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

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



Cranial cluiracters. — 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 vertebra? 42; hind foot 20. 

 Skull of t</]>(> : 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. Ifrft, C? a( l-> 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 by the flatter palate with shallower lateral pits, and by 

 thicker pterygoids ; condyloid process of mandible slightly shorter ; 

 dentition not different. 



Measurements, — Type: Total length 1S4 ; tail vertebras 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 10; mastoid breadth 12.2; alveolar length of upper molar 

 series 6.5. 



Microtus pennsylvanicus labradoiius subsp. nov. 



Type from Ft. Chimo, Ungava, Labrador. No. \\\\, + ad., Merriam 

 Coll. Collected Nov. 15, 1882, by L. 31. Turner. 



General characters. — Size and proportions approximately as in Microtus 

 drummondi. Skull flatter 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 



