110 Bailey North American Species of Sigmodon. 



Distribution. West coast of Mexico from Tepic to southern Sonora. 



Specimens examined. Total number 16, from the following localities: 



Sinaloa: Sierra tie Choix 6, Culiacan 1, Rosario 1, Plomosas 1. 



Tepic: Acaponeta 2, Tepic 1, San Bias 1. 



Sonora: Alamos 3 (not typical). 



Remarks. This largest North American species of Sigmodon occurs 

 with alleni at San Bias, Tepic, and while it may be quite distinct from 

 its nearest congeners, berlandieri and mascotensis and does not appear to 

 overlap the range of either, it unquestionably belongs to the same general 

 group and should stand as a subspecies. 



Sigmodon hispidus toltecus Saussure. 



Hesperomys toltecus Saussure, Rev. et Mag. de Zool. XII, p. 98, 1860. 



Type locality. Mountains of the state of Vera Cruz, Mexico. 



General characters. Conspicuously smaller and darker colored than 

 berlandieri; molars and audital bullae relatively smaller. 



<70for. Upperparts dull brownish gray; belly whitish; feet dark gray, 

 not yellowish or brown; tail bicolor, gray below, blackish above. 



Skull. Smaller than that of berlandieri with much smaller bullae and 

 molars. 



Measurements. Average of 8 adults from Orizaba, Vera Cruz: total 

 length 235; tail 100; hind foot 28. Skull (No. 58,226, $ ad. from Ori 

 zaba): basal length 29.5; nasals 13; zygomatic breadth 18; mastoid 

 breadth 13; alveolar length of upper molar series 6. 



Distribution. Eastern Mexico from Alta Mira, southern Tamaulipas to 

 Orizaba, Vera Cruz. 



Specimens examined. Total number 54 from the following localities: 



Vera Cruz: Orizaba 17, Chichicaxtle 4, Mirador 1. 



Tamaulipas: Alta Mira 12. 



San Luis Potosi: Valles 7. 



Puebla: Metlaltoyuca 13. 



Remarks. This is the only known species of North American Sigmo 

 don of which I have not been able to examine the type or topotypes. 

 As no more definite type locality was assigned than the mountains of 

 Vera Cruz, I am assuming that the Orizaba specimens are typical, an 

 assumption that seems safe in view of the wide range of the form, and 

 the fact that no other species is known to occur in the general region, 

 and that the characters assigned in the original description do not dis 

 agree with those of the present series of specimens from localities cov 

 ering most of the state of Vera Cruz. Specimens from as far north as 

 Alta Mira, Tamaulipas, are indistinguishable from the Orizaba series, 

 but farther north they seem to grade into berlandieri, while in the lower 

 country of southern Vera Cruz they run into saturatus. 



