1890.] 



EXPRESS GEOGRAPHICAL DISTRIBUTION. 



609 



The only irregularity of importance is in the Xearctic region- 

 There the Canadian subregion is to the north of three other sub- 

 regions, and the figure 1 is placed vertically above 2, 3, 4. 



Nearctic 1. Canada. 



2. California. 



3. Rockies. 



4. Eastern States. 



The distribution of an animal or of a group is represented by 

 writing in their proper positions the subregions in which the animal 

 or group occurs. Thus a universal distribution is indicated by 

 fig. 3. A partial distribution, for instance the distribution of the 

 Lemurs, is given in fig. 4. 



3. 



Fig. 



1 

 2 3 4 



1 3 



2 4 



1 3 



2 4 



3 



4 



1 3 



2 4 



1 3 



2 4 



Fig. 4. 



The formula represents the facts almost as faithfully as does a 

 coloured map. It can be written and copied with the utmost 

 rapidity, and it can be printed without engraving by the use of type- 

 lines. Elaboration is easy, but the simplicity of the formula in its 

 present form seems an advantage. 



