MAMMALS OK THE MEXICAN BOUNDARY. 



405 



Type-locality. — Texas, near the Rio Grande. "I procured this lit- 

 tle animal on the Rio Grande near El Paso." (S. W. Woodhouse.) 

 (Type, skin in alcohol and fragments of skull, Cat. No. jV^Aj 

 U. S. National Museum.) 



Geographical range. Inhabits the Sonoran Zone of the Middle 

 Texas Tract. It has been found at San Antonio (Attwater), and 

 from Bee County to Kinney County, along the Rio Grande. 



Fig. 82.— Peromyscus texanus. Skull, a, dorsal view; 6. ventral view: r, lateral view. 



Description. — Similar in proportions to Peromyscus hucopus 

 (Rafinesque). Color above drab-gray, with a dark vertebral area, 

 where the pelage is thickly lined with black. Feet and under parts 

 pure white; tail bicolored, blackish above, white below: ears and 

 tail well coated with hair; soles of feet densely pilose posteriorly. 

 Mammas, three pairs. 



The young, which are born at all seasons of the year, are slate- 

 gray, with whitish under parts, bicolored tails, and the usual black 

 spot on the ear. The young acquire the adult 

 pelage in precisely the same maimer that Peromys- 

 cus rrernicus does (see'p. 433), it beginning on he 

 under surface, extending to the flanks, and thence 

 across the middle of the back, leaving the rump 

 and nape to be covered last. Length, 17.1 mm.; 

 tail vertebras, 75; ear from crown, L2; hind foot, 

 21. Skull, 20.5 by 13.5. Teats, g. 



Cranial and <h ntal charactt rs. — The skull f fig. 82) 

 is narrow,. slender, and rectangular, with the brain- 

 case low and elongated, and the rostral portion 

 long. The teeth (fig. S3) are much smaller than 

 those of /\ tornillo, with which it Lntergrades on the west. 



Remarks. — This mouse, though similar in appearance to Peromys- 

 cus mearnsii (Allen), may be readily distinguished from that species 

 by its smaller, more hairy ears and its much shorter, more hairy, 



Fig. 83.— Peromyscus 

 texanus. Crowns of 

 molar teeth, a. low- 

 er SERIES, b, VI PER 

 SERIES. 



