Still another ant that ha> acquired a footing in tropical Florida, and 

 probably also in other localities in the ( iulf States, is Prcnolepis lon^i- 

 cuntis. It has long hern a common species in the green-houses of 

 temperate Humpe and America. In some of these, as in the Jardin des 

 I Mantes in 1'aris, it has been a permanent resident for more than forty 

 years. In the city of Xe\v York it may sometimes be found even on 

 the top Moors of the great apartment buildings. Wasmann (1905.;;) 

 and . \ssmuth (1907) give good reasons for believing that the original 

 home of this ant is India, and that it has been carried to all parts of 

 the tropics in ships. They show that it has been accompanied in its 

 wanderings by two myrmecophiles, a Lathridiid beetle (Colnoccra 

 and a small cricket ( Myrmecophila accri'omm var. flaro- 

 The peregrinations of Tapinoma melanocephalum, which also 

 occurs in northern dwellings and green-houses, are similar to those of 

 P. longicornis. 



The foregoing sketch of the distribution of North American ants 

 shows that our fauna is very rich in comparison with that of Europe. 

 Nevertheless it must be admitted that we have few distinctive types 

 apparently only the specialized parasitic genera Epoccus, Syininyniiica. 

 Sywipheidole and Epipheidole, the subgenera Dichothorax and Acantho- 

 inyops and the ancient relicit Proceratium. Kobelt has been led by his 

 studies on the distribution of other animals to the conclusion that our 

 existing North American fauna, like that of other countries, "apart 

 from the introduced and feral domestic animals and the English spar- 

 row has shown no evidence of enrichment since the diluvial period. 

 The present is a depauperate diluvial fauna. America, too, proves that 

 we are not living in an incipient, but in a declining geological epoch, not 

 at the beginning of a youthful, creative Quaternary, but at the close of 

 the Tertiary period, whose generative power has been extinguished." 

 This statement may not be strictly true of dominant insect groups like 

 the Formicidse. Not only is it probable that our fauna is being slowly 

 but continually enriched by accessions from the tropics, but a com- 

 parison of the list of North American ants at the end of this volume 

 with the lists of European species compiled by Mayr, Forel, Emery, Ern. 

 Andre and others, shows that the related and identical species of both 

 continents have a greater number of subspecies and varieties in Xorth 

 America. This would seem to force us to the conclusion that mam 

 of our ants are actually in a mutational or premutational phase. 



Turning from this more general, faunistic account to the etho- 

 logical distribution of ants, we observe considerable differences in the 

 frequency with which the colonies occur within the range of each 

 species. When we thus concentrate our attention on a single form. 



