490 



^^^^EELER. 



Calyptomyrmex 

 *STRUMIGENYS 

 *EPITRITUS 



Orectognathus 



Epopostruraa 



Rhopalothrix 

 *DOLICHODERUS (subgen. 



HYPOCLINEA) 



Leptomyrmex 



Frogattella 



Turneria 



*IRIDOMYRMEX 

 *BOTHRIOMYRMEX 

 *TAPINOMA 

 *Technomvrmex 



Acropyga 

 *Plagiolepis 

 *Acantholepis (subgen. Stigmacros) 



Prolasius 



Melophorus 

 *Pseudolasius 



Notoncus 

 *Oecophylla 



Myrmecorhynchus 

 *PREXOLEPIS 



Opisthopsis 



Echinopla 



Calomyrmex 

 *CAMPONOTUS 



Polvrhachis 



Of the 75 genera in this list 31 or 41.3% are known to exist or have 

 existed in Europe and 27 or 36% in America; 37 or 49.3% are unknown 

 in either of these regions, but more than half of them are represented 

 in the Oriental region. As the migration of ants from the latter region 

 into Australia since its isolation has been very much restricted, these 

 genera must also be regarded as of Mesozoic origin. It should also 

 be noted that 21 or 28% of the 75 Australian genera belong to the 

 most ancient and primitive subfamily of the Ponerinae, a group com- 

 parable to the Monotremes and Marsupials among mammals and 

 one which reaches no such proportions in any of the other geographi- 

 cal regions. I believe, therefore, that we have underestimated the 

 antiquity of the genera of ants and that the great majority of them are 

 of Pretertiary or at the latest of early Eocene development. The 

 same may be true even of certain species of tropicopolitan or cosmo- 

 politan distribution, ^. g. Solenopsis geminata, Odontomachus haematoda 

 and esp^ially Camponotus {Myrmoturba) macidatus, which is repre- 

 sented by numerous local races and varieties not only on all the con- 

 tinents but also on many islands {e. g. Hawaii!). There are good 

 reasons for believing, however, that the great majority of existing 

 species and subspecies are of Postmiocene origin. In North America 

 and Eurasia, at any rate, only subspecies and varieties seem to have 

 developed since the Ice Age. This is indicated by the very small 

 number of varieties common to the Nearctic and Palearctic faunas as 

 compared with the number of common species and subspecies (see 

 pp. 485-486). 



