106 alley North American Species of Sigmodon. 



Oklahoma:: Ft. 'Reno 2, Ft. Cobb 1, Orlando|2, Alva 1. 



Kansas: Cairo 1. 



Remarks. 8. texianus is an intermediate form between the dark, rich 

 hispidus and the very pale berlandicri, grading both ways in accordance 

 with the change from humid to arid climate. Specimens from Okla 

 homa and Kansas are almost equally near to hispidus, while San Antonio 

 and Corpus Christi specimens could just as well be referred to berlan- 

 dieri. 



Sigmodon hispidus berlandieri Baird. 



Sigmodon berlandieri Baird, Proc. Acad. Nat. Sci. Phila., VII, 333, 

 1855. 



/Sigmodon hispidus pallidus Mearns., Proc. U. S. Nat. Mus., XX, 504, 

 March 15, 1897. From El Paso, Texas. 



Type locality. Rio Nazas, Coahuilla, Mexico. 



General characters. About the size of hispidus or averaging a little 

 smaller and much paler; pelage full and soft in winter, thin and very 

 hispid in summer. 



Color. Upperparts light buffy or ashy gray; nose not conspicuously 

 yellowish; belly white; feet light gray; tail distinctly bicolor, light gray 

 below, blackish above. 



Skull. Similar to the skull of texianus; differing from that of hispidus 

 in less arched outline and smaller, more rounded bullae. 



Measurements. (No. 58,074, $ ad., from Jimulco, Coahuila, Mexico): 

 total length 232; tail 105; hind foot 33. Average of 5 adults from Del 

 Rio, Texas: total length 256; tail 113; hind foot 32.5. Skull (No. 58,073, 

 $ ad., from Jimulco, Coahuila): basal length 30.5; nasals 12.3; zygo- 

 matic breadth 19; mastoid breadth 13.4: alveolar length of upper molar 

 series 6.5. 



Distributian. Rio Grande and Pecos valleys from Brownsville to 

 El Paso, Texas, and Carlsbad, New Mexico; south to southern Jalisco, 

 Mexico. 



Specimens examined. Total number 200, from the following localities: 



Texas: El Paso and vicinity 7, Guadalupe Mts. 4, Langtry 3, Painted 

 Caves 3, Del Rio 7, Sycamore Creek 3, Eagle Pass 7, Santa Tomas 27, 

 Sauz 2, Brownsville 20, Ft. Clark 3. 



New Mexico: Carlsbad 3. 



Chihuahua: Juarez 1, Chihuahua City 18, Santa Rosalia 8, Presidio 

 del Norte 1. 



Coahuila: Rio Nazas 1, Jimulco 2. 



Nuevo Leon: Doctor Arroyo 1. 



Tamaulipas: Nuevo Laredo 7, Matamoras 11, Camargo 26, Victoria, 2, 

 Jaumave 6, Soto la Marina 9. 



San Luis Potosi: Hda. La Parada 3, Villar 1, Jesus Maria 1, Molino 1. 



Queretaro: Tequisquiapam 1. 



Zacatecas: Valparaiso Mts. 3. 



