12 University of California Publications in Zoology [Vol. 21 



A specimen from Rio Dell, Humboldt County, was referred by 

 Bailey (loc. cit., p. 35) to calif ornicus, but from the close proximity 

 of this place to Cuddeback, there seems good reason for considering it 

 as belonging to constrictus instead. Unfortunately no specimens are 

 so far available from the region between Cuddeback, Helena, Yolla 

 Bolly Mountain and Laytonville. The area of intergradation between 

 constrictus and eximius remains to be shown. Thus specimens from 

 Laytonville exhibit certain characters which indicate that this area 

 may begin in that vicinity. Specimens from Helena are undoubtedly 

 true eximius. 



Microtus californicus eximius, new subspecies 

 Sanhedrin Meadow Mouse 



Arvicola riparius, Townsend (1888, p. 176). Mount Shasta, Siskiyou 



County. 

 Microtus edax, Elliot (1898, p. 204), part. Snow Mountain, Colusa County. 

 Microtus californicus, of various authors, part. 



Type specimen. — Male adult; no. 20098, Mus. Vert. Zool. ; Lierly's 

 Ranch, 2340 feet altitude, 4 miles south of Mount Sanhedrin, Mendo- 

 cino County, California; August 22, 1913; collected by Charles L. 

 Camp ; original no. 1299. 



Range. — Northwestern California (excepting a narrow coasts.! 

 strip from Cape Mendocino north to Oregon line), and south-central 

 Oregon ; from Olema, Marin County, California, east to Rumsey, Yolo 

 County, and north to Drain, in the Umpqua River Valley, Oregon. 

 Vertical range from sea level up to 7500 feet; zonal range Upper 

 Sonoran and Transition. (See map.) 



Total number of specimens examined, 122, from the following 

 localities in California. Marin County : Inverness, 9. Sonoma 

 County : Duncan Mills, 1 ; Freestone, 23 ; Guerneville, 3 ; Cazadero, 9. 

 Mendocino County : Gualala, 5 ; Mount Sanhedrin, 7 ; Mendocino City, 

 12; Willits, 2; Covelo, H. Tehama County: Lynn Mountain, 2; 

 2 miles south of South Yolla Bolly Mountain, 3. Trinity County: 

 Helena, 9. Shasta County: Tower House, 10. Siskiyou County: 

 Mayten, 14; Scott River, 1. Napa County: Mount St. Helena, 1. 



Diagnosis. — Size medinm (hind foot 20 to 24 mm., condylobasal 

 length of skull in largest individuals, 30.2 mm.) ; second upper molar 

 with open posterior lobe or loop ; skull rather narrow as compared 

 with californicus (ratio of zygomatic breadth to condylobasal length 

 about 58%), and feebly ridged in adults; interorbital region not 

 developing single median ridge with age. 



Color. — Mass effect of dorsal area ranging from cinnamon-brown 

 to tawny-olive, darkened more or less by long dark overhairs. In 

 fresh pelage: Light tipped hairs of upperparts of a peculiar ochra- 



