MICROTUS. 301 



mammae four to eight, two or four pectoral and two or four inguinal; 

 normal number eight ; plantar tubercles six ; soles moderately hairy. 



KEY TO SPECIES AND SUBSPECIES OF THE SUBGENUS. 



A. Size small. (Mammae four.) 



a. Above dark brown and black; beneath chest- PAGE 

 nut fulvous M. julviventer 301 



b. Above mixed cinnamon; beneath buffy M. mexicanns 301 



c. Above bistre and black; beneath plumbeous, 



tinged with drab M. m. pkcnis 302 



B. Size large. (Mammae eight.) 



a. Above dark tawny M. c. hyperythrus 302 



303. fulviventer (Microtus), Merr., Proc. Biol. Soc. Wash., xn, 



1898, p. 106. 

 FULVOUS-BELLIED MEADOW VOLE. 



Type locality. Cerro San Felipe, State of Oaxaca, Mexico. Alti- 

 tude, 10,200 feet. 



Geogr. Distr. State of Oaxaca, Mexico. 



Genl. Cliar. Similar to M. mexicanus, but redder. 



Color. Above dark brown and black; under parts chestnut ful- 

 vous; tail blackish above, pale fulvous beneath. 



Measurements. Total length, 154; tail vertebrae, 38; hind foot, 

 20. Skull: basal length, 25.4; length of nasals, 7.4; zygomatic width, 

 15.5; mastoid breadth, 12.4; length of upper molar series, alveolar 

 border, 6.5. 



304. mexicanus (Hcmiotomys), Sauss., Rev. Mag. Zool., 2me Se"r.. 



1861, p. 3. 

 MEXICAN MEADOW VOLE. 



Type locality. Mount Orizaba, State of Puebla, Mexico. 



Geogr. Distr. Eastern part of State of Puebla, Mexico. 



Gcnl. Char. Size small ; tail short ; ears large. Skull broad ; incisive 

 foramina wide and short; first lower molar with six interior salient 

 angles; mammae four, two inguinal, two pectoral. 



Color. Above mixed cinnamon and black, paler on sides; beneath 

 buffy; sides of nose cinnamon; tail above dusky, gray below; feet 

 gray. The above is properly the winter pelage, that of summer 

 being darker. 



Measurements. Average of 10 adults: Total length, 138; tail 

 vertebrae, 29; hind foot, 19.35; maximum, 148; 30; 20. Skull: basal 

 length, 24.5; zygomatic breadth, 15.3; mastoid width, n.6; length 

 of nasals, 7.4; length of upper tooth row, alveolar border, 6.6. 

 (Bailey, N. Am. Faun., No. 17.) 



