678 PROCEEDINGS OF THE ACADEMY OF [Sept., 



Peromyscus eremious (Baird). Desert Mouse. 



Two forms of white-footed mice were obtained by -Mr. Rhoads, and 

 typical examples of each were submitted to Mr. W. H. Osgood, of the 

 V. S. Biological Survey, who has kindly identified them. 



The present species was abundant in the Cocopah Mountains, where 

 a series of nineteen specimens was secured. A single female was ob- 

 tained at the mouth of the Hardy, doubtless carried down in the flood, 

 and four were trapped in the hills near the IMexican boundary, on the 

 Colorado river. 



"A rock-loving mountain species, whose haliitat touches upon but 

 not invades that of sonoriensis." 



Peromyscus sonoriensis (Le Conte). Sonora White-footed Mouse. 



This was the prevalent form in the low ground, nineteen specimens 

 being obtained at the mouth of the Hardy and five others on the Colo- 

 rado thirty-five miles below Yuma. Four specimens were also trapped 

 in the Cocopahs with the preceding species. 



"Excessively abundant in the bottoms, preventing the capture of 

 other small rodents, etc., by incessantly springing the traps. Without 

 studying its anatomy, I should predict that this species was more nearly 

 related to gossypinus of the East than to leucopus. I base this view- 

 solely on its habitat and manner of life." 



Perognathus penicillatus angustirostris Osgood. Slender-nosed Pocket Mouse. 



Three specimens from the Cocopahs and one from the Colorado river, 

 near the Mexican boundary. In going over the large series of these 

 mice in the Rhoads collection at the Academy, I find among them three 

 examples of P. fallax pallidus Mearns, obtained at Mission Creek, 

 California, by R. B. Herron. These, as their labels show% had been 

 separated in 1895 as a distinct race of fallax by Mr. Rhoads, but his 

 name has remained in manuscript and the specimens were afterward 

 referred by him to this species. 



Perognathus spinatUS Merriam. Spiny Pocket Mouse. 



Eleven examples, all from the Cocopah ^Mountains. 



"This and the former named inhabit the desert mountain and plain 

 to the edge of the delta bottoms. Their homes are made by tunnelling 

 at the base of greasewood and other low thickset bushes, as well as 

 among the rocky clefts of the hills where any vegetation has a foothold. 

 The entrances to these burrows remain open. They do not plough 

 underground as Blarina, Scalops, Thomomys, etc., but excavate and 

 throw out the dirt largely at the mouth of the burrow, thus raising the 

 vicinity of their bush colonies into slight mounds. Both species may 



