86 Bailey — New Species and Subspecies of Voles. 



163; tail vertebrae 37 ; hind foot 20.6. Skull of type: Basal length 27.4; 

 nasals 8; zygomatic breadth 1(5.7; mastoid breadth 12.2; alveolar length 

 of upper molar series '1.5. 



Microtus insularis sp. nov. 



Type from Great Gull Island, New York, No. f|jr§, $ im., Merriam 

 Coll. Collected Aug. (i, 1888, by B. H. Dutcher. 



General characters. — Size of pennsylvanicus ; colors darker; skull shorter 

 and wider with spreading zygoma and deep prezygomatic notches. 



Color. — August pelage: Above, dark yellowish bister heavily mixed with 

 black hairs, darkest on nose and face ; belly dusky, washed with cinna- 

 mon; feet blackish ; tail black above, color of belly below. 



Cranial characters. — The skull differs from that of pennsylvanicus in 

 shorter, wider brain case; wider and more abruptly spreading zygomatic 

 arches; broader zygomatic shield; smaller audita! bullae; palate short 

 with a median point or spur and deep lateral pits. Posterior upper molar 

 with second inner and outer angles approximately opposite and conflu- 

 ent; dentition otherwise similar to that of pennsylvanicus. 



Measurements. — Type, measured from dry skin : Tail 2!); hind foot 20- 

 Skull, No. 43969, from Little Gull Island: Basal length 26; zygomatic 

 breadth, 16.2; mastoid breadth 12.3; alveolar length of upper molar 

 series 6.8. 



Microtus angusticeps sp. nov. 



Type from Crescent City, California. No. H§oi> c? a ^-, U. S. Nat. Mus., 

 Biological Survey Coll. Collected June 16, 1889, by T. S. Palmer. Orig. 

 No. 151. 



General characters. — Smaller and darker than typical mordax, with very 

 narrow, slender skull and small audita! bulla 1 . 



Color. — Summer pelage : Upper parts dark bister, lined with black hairs, 

 darkest on face and nose ; sides paler; belly washed with creamy white ; 

 feet plumbeous-gray; tail distinctly bicolor, blackish above, soiled white 



below. 



Cranial characters. — Skull small and very narrow, distinctly ridged in 

 adults; nasals projecting in front of incisors; incisive foramina short; 

 audital bulhe very small and constricted ; coronoid notch of mandible 

 narrow; incisors slender; molars small with narrow, sharp angles; 

 enamel pattern as in M. moi'dax. 



Measurements. — Type, $ ad. : Total length 170 ; tail vertebra? 56 ; hind 

 foot 22. Skull of type: Basal length 23.4; nasals 7.6; zygomatic breadth 

 13.5; mastoid breadth 10.8; alveolar length of upper molar series 6. 



Microtus nevaderrsis sp. nov. 



Type from Ash Meadows, Nye Co., Nevada. No. UUh 9 ad., U. S. 

 Nat, .Mus., Biological Survey Coll. Collected March 2, 1891, by E. W. 

 Nelson. Orig. No. 577. 



