No. 615] INHERITANCE IN PEBOMYSCUS 181 



ments of the physical environment which were responsi- 

 ble for the presence of the same subspecies under such 

 widely divergent conditions of life. Particularly is this 

 true when the environmental differences, as in the present 

 case, far exceed those between the habitats of certain 

 quite distinct subspecies. 



Nor does the contention seem justified that such ex- 

 tensity in the distribution of a single subspecies is fully 

 accounted for by the absence of any insurmountable bar- 

 riers to its dispersal. So far as geographic features are 

 concerned, the barriers between the range of gambdi and 

 the ranges of certain neighboring subspecies seem to be 

 no greater than some of those which traverse the terri- 

 tory of f/anibcU itself. Looking at the distribution maps 

 in such publications as those just mentioned, one is im- 

 pressed by a seeming analogy between the boundaries of 

 these various subspecific ranges and those of the political 

 subdivisions of the earth's surface. In considerable de- 

 gree these last are bounded by geographic features, but to 

 a large extent, also, the lines of demarcation seem to be 

 drawn quite arbitrarily— the territories merely bound 

 one another. 



mile great weight must be given to the findings of 

 these taxonomic experts, I think it is our duty at present 

 to accept certain of their conclusions with considerable 

 reservation. This is particularly true of assertions as 

 to the absolute identity of the characters of specimens 

 from widely different parts of a given range. The pub- 

 lished data make it plain that the authors are in no posi- 

 tion to detect minor differences of a statistical nature. A 

 small number of specimens from each locality are com- 

 monly compared, the measurements "in the flesh" of the 

 various specimens necessarily having been made by a 

 number of different collectors. It will be evident from 

 the ensuing pages that the differences with which we are 

 dealing are often of such a nature as to be revealed only 

 by the comparison of large numbers of individuals, meas- 

 ured according to uniform standards. As regards the 



