26 University of California PuMications in Zoology [Vol. 21 



but not extending posteriorly beyond plane of condyle. Peripheral 

 tuberosity over base of incisor lying for the most part within masse- 

 teric ridge, but not conspicuous. Base of mandibular foramen de- 

 cidedly above level of cutting surface of last lower molar. Mental 

 foramen on lateral face situated somewhat below superior surface 

 of diastema. 



Teeth. — Molars both above and below differing from those of cali- 

 f amicus in the general tendency of enamel folding of closed triangles 

 to assume more irregular outlines. Anterior loop of M- flattened. 

 An internal lobe present on posterior triangle of M-. The enamel 

 folding of ]\I- without any marked peculiarity excepting that terminal 

 loop is rather long and external side rather straight. 



Lower molars not exhibiting any marked peculiarities excepting 

 that transverse loops are relatively large. Anterior loop of M^ deeply 

 notched by internal reentrant angle. 



Remarks. — This race has apparently been exterminated within 

 recent years, as the type locality, a small tule marsh near Shoshone, 

 Inyo County, has been burnt over for several consecutive years and 

 is now used for a hog pasture. Assiduous trapping at this point in 

 May, 1917, did not yield a single meadow mouse {fide Grinnell, MS, 

 and Storer, MS). There is a possibility, however, that M. c. scirpcnsis 

 may still exist south of Shoshone near the town of Tecopa, where there 

 is permanent water and tule marshes. 



The characters possessed by this race show that it is an isolated 

 form of the calif ornic us group. It is probable that the calif or nicus 

 group had a continuous distribution over the state at one time and 

 that geological changes have resulted in isolating certain stocks from 

 one another. Scirpensis resembles both aestuarinus and vallicola, but 

 neither can be considered as the parent stock. It is a remarkable 

 race because of its occurrence away from the main mountain axes 

 and in an area of extremely high summer temperature. 



Microtus californicus kernensis, new subspecies 

 Kern River Meadow Mouse 



Arvicola (Myonovies) riparius, Coues and Allen (1877, p. 173), part. Fort 



Tejon. 

 Microtus californicus, of authors, part. 



Type specimen. — Female adult ; no. 15779, Mus. Vert. Zool. ; Fay 

 Creek, 4100 feet altitude, Kern County, California; July 14, 1911; 

 collected by Tracy I. Storer ; original no. 219. 



Range. — Kern River basin, from Taylor Meadow, Tulare County, 

 west to Bakersfield and Fort Tejon, Kern County. Vertical range 

 from 400 feet up to 7000 feet; zonal range Lower Sonoran to Tran- 

 sition. (See map.) 



