174 



TBE AMERICAN NATURALIST 



[Vol. LI 



of racial characters may be largely interrupted. It is the 

 object of this paper to discuss a case of this sort which 

 I have had the opportunity of studying during the past 

 year. 



The subspecies Peromyscus maniculatus rubidus, ac- 

 cording to Osgood,^ who first described it, occupies a strip 

 of varying width on the ''coast of California and Oregon 

 from San Francisco Bay to the mouth of the Columbia 

 Kiver." In discussing certain local variations shown by 

 this subspecies throughout its range, the same writer 

 states that ' ' six specimens from the Outer Peninsula, near 

 Samoa, Humboldt Bay, are decidedly paler than others 

 from the neighboring redwoods. They evidently repre- 

 sent an incipient and very local subspecies, and well illus- 

 trate the plasticity of the group to which they belong." 

 Osgood further remarks that ''a careful study of this 

 variation and the local conditions doubtless would prove 

 instructive" (p. 66). 



During the latter part of May, 1916, I trapped on two 

 consecutive nights in the neighborhood from which Os- 

 good obtained his six "aberrant" specimens of rudihus.^ 

 About one hundred live-traps were set on each occasion. 

 Twenty-eight specimens were taken, of which twenty-one 

 were later available for skinning and for careful meas- 

 urement. These last were all in either mature or adoles- 

 cent pelage, and were about evenly divided in respect to 

 sex. 



The distinctness of this race from the ruhidus of the 

 redwood forests on the mainland was evident from a 

 casual inspection of the living mice. A more careful com- 

 parison of freshly killed specimens from the two locali- 

 ties, and later of their prepared skins, justifies the fol- 

 lowing generalizations. These impressions were formed 

 independently by several other persons to whom I showed 

 'he specimens, and were confirmed by more careful ex- 



3 The trapping was done between one and two miles northwest of the 

 village of Samoa. Besides these Peromyscus, the only other animal caught 

 was a single specimen of Microtus. 



