

ANTS. 



above table, aiv represented by very few specimens compared with 

 the boreal genera, is not readily explained by assuming- that a river 

 brought down lowland and mountain forms from Tertiary Scandi- 

 navia and deposited them together in the beds of northern Germany, 

 for on this assumption we should expect to find the lowland or tropical 

 greatly in excess of the boreal specimens. It seems more natural to 

 suppose that during the Lower Oligocene both the extinct and the 

 tropical genera were already reduced to dwindling relicts, though co- 

 existing with the circumpolar ant-fauna which had taken possession 

 of the amber forests. In other words, even at that time the modern 

 genera were far and away the more vigorous and prolific in the Sam- 

 land, which was to become their exclusive heritage after the glacial 

 epoch had wiped out the tropical genera that were leading a precarious 

 existence in the warmer and more sheltered spots. We may assume, 

 therefore, that the greatest development of these southern genera in 

 this northern region occurred during the Eocene or even during the 



FIG. 98. \Yorker of Dimorphomyrmex tlicryi of the Baltic Amber. (Emery.) a, 

 From the right side ; b, head from above. 



Mesozoic and that the adverse conditions, which culminated in the 

 glacial epoch, were already beginning to destroy the older, tropical 

 components of the Lower Oligocene fauna. 1 



To this consideration of the amber ants a few remarks on some of 

 the more interesting genera and species may be appended : 



i. Poncriiuc. The most conspicuous of these is the large Priono- 

 inynnc.r longiccfs (Fig. 88) of the Prussian amber. Mayr described 

 this species from a single specimen and I have found several more in 

 the collections loaned me by Professors Klebs and Tornquist. This ant 

 is allied to the Australian Mynnccia, the most primitive of living 

 Formicidse, but is even less specialized in the structure of the mandibles 

 and abdominal pedicel. Another interesting but much smaller species is 

 Kradofioncra uicicri (Fig. 89), which foreshadows our modern species 



1 Since these lines were written, I have found in one of the Konigsberg col- 

 lections a single block of amber containing a tropical Dolichodcrus and a speci- 

 men of Formica flori. These ants, therefore, not only nested in the same 

 locality, but foraged on the same tree. 



