The Ants of the Baltic Amber. 
13 
punctatus of Europe, is represented by 494 specimens. Subtracting 
this number also from the 4961 specimens, we have left only 1190 
specimens to represent all the remaining species and genera. It will 
be seen, theref'ore, that most of the species of truly extra-European 
affinities were rare in the amber forests and that the most abundant 
ants, apart from the two species of Iridomyrmex, belonged to Formica 
and Lasius, which are even today the two dominant European genera 1 ). 
A pronounced tendency towards a supplanting of the Indian, Malayan 
and Australian elements in the mixed amber fauna by palearctic ele- 
ments is therefore very apparent as far back as Lower Oligocene 
times, although it seems to have been permanently accomplished only 
by the advent of the Glacial Epoch. 
The foregoing considerations suggest several questions that are 
not easily answered. Did all the amber species coexist as members 
of a single fauna throughout the life-time of the amber forests or did 
they belong to successive faunas, the Indomalayan and Australian 
elements belonging to an earlier and warmer, the palearctic to a later 
and cooler portion of the Lower Oligocene? Or were the differences 
of altitude or latitude or of both in the amber forests sufficient to 
produce two different faunas which coexisted though occupying diffe- 
rent stations? Answers to these questions can come only from a more 
precise knowledge of the conditions under which the amber was formed 
and preserved. That the amber forests were rather extensive is clear 
from Tornquist’s Statement 2 ) that their Southern boundary extended 
a cross what is now central S weden eastward through Finland and 
Estland and up the Dvina River to Minsk and Tobolsk in Western 
Russia, while the adjacent sea covered not only what is now northern 
Germany but also the region drained by the Vistula, Niemen and 
Dnieper Rivers as far as the Black Sea. That the climate of the 
amber country was subtropical is evident from its Vegetation. Some 
of the earlier paleontologists, like Heer, were convinced that the country 
was not flat, but mountainous, and that the masses of hardened amber 
were detached from the trees and with other vegetable detritus carried 
down by torrents to the region in which they are now found, namely 
the bed of the Baltic Sea and the soil of northern Germany which 
it once covered. 
1 ) Prenolepis is still a dominant genus in North America and tropical Asia but 
has ceased to occupy this position in Europe. 
2 ) Geologie von Ostpreußen, 1910. 
