428 



BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Geographical range. — Lower California Tropical or Palm Tract, 

 along the east base of the Coast Range Mountains. 



Description. — Similar externally to Peromyscus eremicus (Baird), 

 but smaller, with a longer tail and much paler coloration. Upper 

 surface grayish cream buff, deepening to pale ochraceous buff on 

 sides and rump; tail slightly dusky above, white below, hairy at end; 

 feel and under surfaces white; whiskers mostly colorless; ears and 

 soles naked, the former slightly pubescent. Length, 19."> mm.; tail 



Fifi. 95.— Peromyscus stepiiensi. Skull, o, dorsal view; 6, ventral view; c, lateral view. 



vertebra 1 , 108 (to end of pencil, 114); ear from crown, 16; ear from 

 notch, 18.5; length of head, 26.5; length of hind foot, 19. Skull, 23 

 by 11.5. 



Cranial and dental characters. — The skull (fig. 95) is strongly 

 depressed anteriorly, with the rostrum produced and the nasals pro- 

 jecting. The zygomatic arches are incurved and convergent anteri- 

 orly to meet the sloping zygomatic processes, this feature recalling 

 the configuration of .young skulls of the other 

 species of Peromyscas, in which the brain case 

 has outgrown the face, though in this case We 

 have the opposite condition, the facial portion 

 being unusually elongated. In P. stephensi the 

 profile of the skull is nearly straight above, 

 declining to the front. The skull is remarkably 

 narrow interorbitally. The teeth are shown in 

 fig. 96. 



Remarks. — A specimen of this species in the 

 American Museum collection (f|§| male adult, old) agrees in all 

 respects with the type, and was collected at Palm Springs, San Diego 

 County, California (Colorado Desert), February 19, 1893, by Mr. F. 

 Stephens, for whom the species is named. "Total length, 181; tail 

 vertebra' 110; hind foot, 19." Peromyscus eremicus occurs with the 

 present species at Palm Springs. 



Local distribution. The type was caught May 8, 1894, among 

 granite bowlders at the first water in the canyon through which the 



Fig. 9fi.— Peromyscus ste- 

 phensi. Crowns of 

 molar teeth (i. i ( >\v er 

 series; I), upper series. 



