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Univ( rsity of California Publications in Zoology L VoL - 10 



as recurring periods of extreme food shortage, epidemic disease, 

 and cataclysmic disturbances of either climate or topography. 



Table (1) showing relative numbers of boreal mammals represented 

 on the different mountain masses of southern California. Note the 

 correlation of numbers of types with sizi of tin detached area of Boreal 

 (and Transition) zone in each ease (see profile, pi. 7). 



Marmota flaviventer x 

 ( allospermophilus chrysodeirus, 



subsp. x 



Eutamias alpinus x 



Eutamias speciosus, subsp. x 



Sciurus griseus, subsp. x 



Sciurus d. albolimbatus x 



Sciuropterus alpinus, subsp. x 



Neotoma c. cinerea x 



Microtus m. dutcheri x 



Microtus mordax, subsp. x 

 Thomomys alpinus -j- T. alti- 



vallis x 



Zapus t. alleni x 



Erel hizon epixant hum x 



< >chotona albatus x 



Lepus c. sierrae x 



Canis lestes x 



\ T ulpes neeator x 



Gulo luteus x 



Mustela a rizonensis x 



Neosorex p. navigator x 



Total number of species 20 



