296 University of California Piihlications in Zoology [Vol. 21 



very closely the typical condition in angusticeps. In comparison with 

 sierrae, the molariforni teeth are lighter and the bullae smaller. The 

 angularity of the skull and the shape of the zygomata are in most 

 respects intermediate in character between angusticeps and sierrae. 

 Externally the specimens in question are more richly colored than 

 in sierrae, though the tail is not noticeably bicolor. In size they are 

 as large as old adults of sierrae. 



According to current usage it is not permissible to recognize two 

 subspecies of the same species in the same region. To regard these 

 large individuals as either sierrae or mordax would lead to the anom- 

 alous situation of two subspecies of the mordax group occurring in the 

 same area and living in the same ecological association, which is hardly 

 in keeping with our present ideas regarding speciation. The most 

 satisfactory disposition of these large specimens would seem to be 

 to refer them to angnsticeps and to recognize the fact that they are 

 individual extremes intermediate in character between the latter and 

 sierrae. 



Microtus mordax bernardinus IMerriam 

 San Bernardino Meadow Mouse 

 Microtus mordax hernardinus Merriam (1908, p. 145). 



Type specimen. — Male adult; no. 150632, Biol. Surv. coll., U. S. 

 Nat. Mus. ; Dry Lake, 9050 feet altitude, San Bernardino Mountains, 

 San Bernardino County, California; August 21, 1907; collected by 

 Vernon Bailey ; original no. 8749. 



Range. — San Bernardino Mountains of southern California. Ver- 

 tical range from 7500 feet to 9050 feet ; zonal range Transition through 

 Canadian. (See map, fig. CC.) 



Total number of specimens examined, 47, from the following locali- 

 ties in California. San Bernardino County: South Fork Santa Ana 

 River (8500 feet), 6; Bluff Lake (7500 feet), 41. 



Diagnosis. — Size medium (hind foot, 21 to 23 mm. ; condylobasal 

 length of skull in largest individuals, 28.2 mm.). As compared with 

 Microtus mordax sierrae, skull smaller, zygomata narrower and shorter, 

 brain case less ridged, and with relatively longer rostrum (ratio of 

 zygomatic breadth to cond.ylobasal length about 57 per cent) and not 

 conspicuousl}^ ridged in adults ; incisive foramina wide open, not con- 

 stricted posteriorly; auditory bullae slightly smaller than in sierrae; 

 pelage dark and usually dull; ears smaller than in sierrae (10 to 

 12 mm.). 



Measurements.— Ay i^ra^Q of 10 specimens : Total length, 183.8 mm. 

 (170-198); tail vertebrae, 62.6 mm. (53-68); hind foot, 22.4 mm. 

 (21-23) ; condylobasal length, 27.07 mm. (26.2-28.1) ; occipito-nasal 



