MAMMALS OF THE MEXICAN BOUNDARY. 



3<>3 



Cranial and <1< ntal characters. — The skull (fig. 71) of Peromyscus so- 

 noriensis rujinus differs IVonith.it of P.li ucopus in having thezygomal if 

 arches elbowed out in front in such a manner that the skull is wider 

 anteriorly than posteriorly, the reverse being true, as a rule, of /'. 

 leucopus. The upper profile of the skull is less Hat than that of P. 

 h ucopus, being highesl interorbitally, t hence sloping sharply downw ard 

 in front and behind. There arc somewhat prominent supraorbital and 



1 JfW-Ji 



Fig. 71.— Peromyscus sonoriensis rufinus. Skull, a, dorsal view, b ventral view; 



c lateral view. 



temporal ridges which P. leucopus lacks, and the premaxillaries are 

 narrower. The incisive foramen is longer than in P. It ucopus, the 

 interpterygoid fossa longer and narrower, and the mandible has more 

 produced angular and coronoid processes, as in other members of 

 the sonoriensis group. The teeth are shown in fig. 72. 



Habits and local distribution. — This beautiful 

 mouse, which appears to intergrade with the plains 

 mice of the Austral life zone, is actually a foresl 

 animal, living in great numbers in the pine, aspen, 

 and Douglas spruce woods of the Arizona moun- 

 tains. I found it in the Mogollon and San Francisco 

 mountains, frequenting camps, cabins, and every 

 fig" 72 -peromyscus part of the woods. On September 5, 1886, 1 visited 

 sonoriensis rujjn- the ranch of Mr. Charles Ry all, in the Verde Moun- 

 ds. Crowns of . • . r t "«.*i o " t> i fa c.i 



..,,.„ , ttT „ n tains west ol Little Squaw reak. Dozens ol these 



Mi'LAR 1 EETH a u 



lower series, 6. mice were running about the walls, rafters, and 

 . thatching of the log cabin. A pair of slender snakes 

 of the kind called "blue racers" were gliding gracefully aboul the 

 ceiling m the thatch and through crevices between the logs. One of 

 the snakes caught a mouse, and the pursuit had caused the excitement 

 among its companions. On the Mogollon Mountains, August 21, 

 1887, I trapped a pretty wood mouse in a "delusion" mouse trap. 

 Wishing to carry the little beast to Fort Verde, I wrapped the trap m 

 a woolen "fascinator." Upon the road the woolly garment was 

 nibbled and pulled into the trap, where it was cleverly made into a 

 nice warm nest. 



