428 University of California Publications in Zoology | Vou. 17 
same general region have operated in similar fashion, because of the 
soil-moisture maintained thereon. Thomomys perpallidus mohavensis 
and T. p. perpes are valley forms; T. scapterus and T. melanotis are 
montane forms. 
Perodipus mohavensis, new species 
Mohave Kangaroo Rat 
Type.—Male adult, skin and skull; no. 26835, Mus. Vert. Zool. ; 
3275 feet altitude, half mile east of railway station of Warren (about 
five miles north of Mohave), Kern County, California; March 27, 
1917; collected by J. Grinnell; original no. 3942. 
Diagnosis—A medium sized rather small eared, buff-colored 
Perodipus, perhaps nearest like P. panamintinus. Differs from topo- 
types of that form in somewhat smaller size, decidedly smaller ears, 
much more ochraceous-buffy tone of coloration, in less amount of 
black about the face, slightly narrower skull, and in less inflated 
auditory bullae. 
Measurements.—See table 4 (compare with measurements given by 
Merriam, 1894, 1904, and 1907, for the different species of Perodipus 
described by him). 
Distribution—Specimens at hand indicate the presence of this 
form along the western border of the Mohave Desert at least from 
Walker Pass, northeastern Kern County, south to Fairmont, north- 
western Los Angeles County. 
TABLE 4 
MEASUREMENTS, IN MILLIMETERS, OF TEN ADULT SPECIMENS oF Perodipus 
mohavensis, ALL COLLECTED BY J. GRINNELL AND J. DIXON NEAR MOHAVE, 
KERN COUNTY, CALIFORNIA, MARCH 26 AND 27, 1917 
= Eo a 
= > oe ie ee go Vig siHie 
Museum = Pa i He es 2 3 fs = = 
number Sex & a q Sine i AQ o = 
26835* ref Bihy  alyAsh | 2 al 40:7 25.0 15.8 5.2 
26837 J 295 175 44 12 39:4 240 “Wb 5:0 
26839 Jb 290 175 44 i383 39.2 245 14.6 4.7 
26841 Jd 300 180 41 13 40.00 244 15.5 5.3 
26843 Jb 305) 180)” 455) 3 4170) 20.38 Lo 8ieSro 
26830 2 288) 272) 40) W0l5 (3821 Peay MES) hy 
26832 ie) 285 167 43° 12 39.4 248 15.0 4.8 
26834 ie) 295) Lid) 425 eel 39.6 240 148 49 
26840 2 285 170 43 £14 38.3 23.2 146 4.8 
26842 2 300 175 44 138 39.3 24.0 14:9 5.2 
1 Type. 
