272 Uwivcrsity of California Publications in Zoology [Vol. 21 



in the case of either mordax or montanus. Mariposae was found on 

 the south side of the Kings River in the neighborhood of Minkler. 



South of the Kings River Caiion, 3Iicrohts montmius dutcheri, the 

 southern representative of the niontanus group, was not found at 

 Horse Corral Meadows, amid apparentlj^ suitable surroundings for the 

 subspecies {fide Swarth, MS, and Dixon, MS). The northernmost point 

 of record for dutcheri is at Whitney Meadows. The zonal range of 

 both montaniis and mordax extends from Transition to Hudsonian. 



On the face of it, the absence of Microtus nhO)itanus from the 

 Kings River region might appear to some workers as a valid reason 

 for recognizing the race dutcheri as a distinct species; but I, myself, 

 am not so inclined. The main factor governing the dispersal of the 

 Microtus mo-ntanus group in California is the presence of rich soil and 

 swamps or large wet meadows. Alpine meadows are occupied in the 

 southern part of the state, tule swamps and marshes generally in the 

 north, as around Klamath, Goose, and Rhett lakes. The apparent 

 absence of the meadow mouse in question from the Kings River 

 region may be attributed either to a real associational condition wliich 

 is unfavorable, or, as seems unlikely, to the fortuitous circumstance 

 of their having been overlooked by collectors. 



