EXPLANATION OF PLATE 8 



Dorsal and ventral views of crania of four subspecies of Microtus viordax; 

 X 2. 



Microtus mordax angusticeps. 



Figs, la, Ifo. No. 11522, J", Mus. Vert. Zool., 3 miles vilest of Areata, Humboldt 

 County. 



Figs. 2a, 2}). No. 11530, J', Mus. Vert. Zool., 3 miles west of Areata, Humboldt 

 County. 



Microtus mordax l)ernardmus. 



Figs. 3a, 3b. No. 6279, J", Mus. Vert. Zool., BlufP Lake, San Bernardino Moun- 

 tains. 



Figs. 4a, ^1). No. 6285, J', Mus. Vert. Zool., South Fork Santa Ana, San Ber- 

 nardino Mountains. 



Microtus viordax sierras. 



Figs. 5a, 5&. No. 22437, c^, Mus. A^ert. Zool., Tuolumne Meadows, Yosemite 

 Park, 



Figs. 6a, 6&. No. 25052, J", Mus. Vert. Zool., Kings River Canon, Fresno 

 County. 



Microtus mordax mordax. 



Figs. 7a, 7fc. No. 11193, ^, Mus. Vert. Zool., east face Warren Peak, Warner 

 Mountains. 



Figs. 8a, 8&. No. 11166, J', Mus. Vert. Zool., Parker Creek, Warner Moun- 

 tains. 



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