376 NEOTROPICAL PSELAPHIDAE 



This figure of 222,857 species may be said to be adjusted for interfamily 

 competition within the community and this third step (PI. XXI) may be char- 

 acterized as the Competitive Factor. It assumes a more or less perfect equili- 

 bration between food and feeders, and attempts to compensate for the third 

 and fourth postulates previously listed. 



4. This does not take cognizance of the fact that species of Pselaphidae 

 have overlapping ranges. Intrafamily competition should be more severe than 

 interfamily competition since pselaphids would tend to have similar predators 

 and parasites; and their food and niche requirements are satisfied during the 

 same period of the twenty-four hour cycle. Here I have no rule to guide specu- 

 lation. The present maximum of one species per one-tenth square mile may 

 represent one-fifteenth to one-thirtieth the fauna without intrafamily competi- 

 tion. This would postulate 7000 to 15,000 neotropical species adjusted for total 

 competition at this level of integration. 



What has been said here refers to the Range Factor, and all of these in- 

 fluences (PI. XXI) have been treated as operating independently. This is 

 undoubtedly false, as they probably operate jointly at every part of the argu- 

 ment. Furthermore, there is no information upon the effects of human activity 

 upon pselaphids. Such effects obviously exist in populated areas. These effects 

 are certainly adverse and there is every reason to believe that this adverse 

 influence will increase in magnitude. 



Similarly there are no data on the net evolution of pselaphids, that is 

 the relation between the establishment of successful mutants and the ex- 

 tinction of species. 



Nor are the guests of ants and termites properly treated since selection 

 pressures within the nest of the host must be very different from those in the 

 forest floor or tropical grassland. 



The author is aware that different methods of treatment, or rearrange- 

 ment of the same treatment, might be more desirable ; that different values can 

 be set up. The considered maximum of 14,000 to 15,000 species may seem high 

 when not quite 1000 are described, but the figure appears reasonable when 

 we realize how little is actually known of the area estimated. When all insects 

 have been described, the one and a half million described between 1758 and 

 1940 (Metcalf, 1940) will not appear nearly as imposing to us as it does now, 

 when the tropics are just revealing their richness. 



A second question to be asked is, what is the total population of indi- 

 viduals? This is much more readily answered as we have at least one quanti- 

 tative figure. Williams found 26 specimens in thirteen square meters, or one 

 per square meter of leaf mold in the Barro Colorado forest. This works out 

 roughly at 300,000 per square mile. This must be reduced by half to allow 

 for that part of the floor covered by tree trunks, et cetera, but is trebled by the 

 log mold species, the majority of which do not inhabit the leaf duff, but pass 

 the day beneath the loose bark of trees fallen on the ground, and this does not 

 include the ant and termite nest forms which work out at five per cent. This 

 gives a conservative estimate of 465,000 per square mile, for maximum forest 



