Plate XXI 



SOME INFLUENCES PROBABLY OPERATING UPON PSELAPHIDAE 



(For documentation please see text) 



Fig. 1. Theoretical, evenly distributed, taxonomic units at maximum density. 



Fig. 2. Operation of the Subspeciation Factor. The numerous taxonomic units 

 are in reality subspecies of a relatively few species populations. 



Fig. 3. Operation of the Community Factor. The differential biotic potential 

 of the several communities imposes differential distribution and re- 

 duces the number of species populations for the whole area. 



Fig. 4. Operation of the Competitive Factor. Predators in the same stratum 

 of the Eltonian Pyramid compete with pselaphid species popu- 

 lations, for food and shelter, greatly reducing the number of species. 



Fig. 5. Operation of the Range Factor. Species populations of pselaphids over- 

 lap within a given biome. This sets up intra-family competition 

 and may or may not reduce the number of species, depending upon 

 overlap in activity pattern, extra-family competition, et cetera. 



