116 Bailey — North American Species of Sigmodon. 



Sigmodon alticola sp. nov. 



Tyj)e from Cerro San Felipe, Oaxaca, Mexico, at 10,000 feet altitude, 

 No. 68,231, U. S. National Museum, Biological Survey Collection, $ ad. 

 Collected August 24, 1894, by E. W. Nelson and E. A. Goldman. 

 Orginal No. 6624. 



General characters. — Size medium; tail hairy; pelage long and soft 

 both in winter and summer; colors dark and rich except gray ears. 



Color. — Upperparts dark ochraceous or light umber brown; ears clear 

 gray, a little darker than in leucotis; belly pale cinnamon brown; feet 

 yellowish gray; tail black, becoming yellowish brown below at base. 



Skull. — Similar to that of leucotis in form but slenderer, less heavily 

 ridged and narrower interorbitally; interparietal narrow with a dividing 

 suture in middle; supraoccipital without median ridge; nasals narrow 

 and rounded at ends; lateral pits of palate very shallow. 



Mea.sure7nents.— Type: total length 230; tail 101; hind foot 28.5. Skull 

 of type: basal length 28.5; nasals 11; zygomatic breadth 17.8; mastoid 

 breadth 13.5; alveolar length of upper molar series 6.3. 



Distribution. — Mountains of Oaxaca. 



SpecimcTih examined. — Cerro San Felipe 1, 15 miles west of Oaxaca 2. 



Sigmodon alticola amoles subsp. nov. 



Tt/peirom Pinal de Amoles, Queretaro, Mexico, at 7,000 feet altitude. 

 No. 81,430, U. S. National Museum, Biological Survey Collection, $ ad. 

 Collected September 18, 1898, by E. W. Nelson and E. A. Goldman. 

 Original No. 10,161. 



General characters. — Similar to alticola but upperparts duller and less 

 tawny, skull wider interorbitally, with slightly smaller bullae and deeper 

 lateral pits of palate; interparietal narrower but not divided. 



Measurements. — Type: total length 252; tail 105; hind foot 29.5. Skull 

 of type: basal length 29.5; nasals 5.7; zygomatic breadth 19.6; mastoid 

 breadth 14; alveolar length of upper molar series 6.3. 



Distribution. — Known from only 2 specimens from type locality. 



Remarks. — While there seems hardly a possibility of continuity of 

 range across the wide gaps of low country separating the type localities 

 of the two forms, the slight difference of the present -form from alticola 

 does not admit of more than subspecific rank. 



