1922] Swarth: Birds and Mammals of the Stikine Begion 177 



Macrurus, as represented by specimens from the more western 

 islands of the Alexander Archipelago, is a very different looking animal 

 from mordax of the interior. The brown coloration of the one, and the 

 gray of the other, correlated with the differences in size and length of 

 tail, render the two series absolutely unlike. Meadow mice from Mitkof 

 and Wrangell islands, however, are, in color, about midway between 

 the extremes indicated, and the few specimens at hand from the lower 

 Stikine tend still further to bridge the gap. As regards color, it is 

 possible to arrange specimens with regard to geographical position, 

 so as to produce a graded series of changes from one extreme to the 

 other, with no abrupt break at any point. The same is true of general 

 size, and of skull characters. The accompanying diagram (fig. V) 



macrurus 



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rt"oi 



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Fig. V. Diagram showing individual and geographic variation in ratio of 

 length of tail vertebrae to total length in adult long-tailed meadow mice (both 

 sexes). Figures at left of the vertical lines indicate numbers of specimens 

 measured; length of lines shows range of individual variation; points connected 

 by lines mark positions of averages. 



