UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 21, No. 8, pp. 275-302, 1 plate, 29 figures in text April 18, 1922 



A SYNOPSIS OF THE MICROTUS MORDAX 



GROUP OF MEADOW MICE IN 



CALIFORNIA 



BY 



EEMINGTON KELLOGG 



(Contribution from the Museum of Vertebrate Zoology of the University of California) 



INTRODUCTION 



The purpose of the present paper is to give detailed descriptions 

 of the races of the Microtns mordax group that inhabit the state of 

 California, so far as they are recognized up to the present time. This 

 constitutes the third paper of a series by the writer on the Microtinae 

 of California. The restriction of the area treated to the limits of 

 California has resulted in a relatively more critical examination of 

 the races concerned than would otherwise have been possible. 



The writer has expressed his views in regard to the criteria for 

 the employment of the subspecies concept fully in a previous paper 

 (Kellogg, 1922, p. 256), so that there is no need to discuss the mat- 

 ter further in this connection. The Microtus mordax stock is not so 

 amenable, apparently, to diverse conditions of environment as is the 

 Microtus calif ornlcus stock. Our present knowledge of the group 

 indicates that wherever mordax occurs it is the dominant species, 

 restricting the general distribution of any other meadow mouse of 

 the same region, unless conditions be such that each can exist locally 

 without trespassing on the preserves of the other. 



Both Microtus mordax and Microtus calif ornicus are known from 

 the Pleistocene of California in deposits situated within the limits of 

 their present ranges. Data so far gathered are insufficient to give 

 any clue as to their past distribution or as to the factors which led 

 to their present distribution. 



