The Ants of the Baltic Amber. 
15 
this suggests the possible coexistence of different ant-faunas at diffe- 
rent elevations, the fortuitous deposition of pieces of amber of different 
provenience in regions far from those in which the insect inclusions 
were acquired, precludes all argument in favor of the coexistence of 
species found at the present time in the same deposit. It does not, 
however, preclude the possibility of determining the former coexistence 
of species now found together in the same pieces of amber, for it is, 
of course, very evident that simultaneous inclusion could only have 
occurred in the case of forms living at precisely the same time and 
place. Among the materials examined I have noted the following 
instances of such simultaneous inclusion: 
Iridomyrmex gcepperti with Dolichoderus tertiarius 
I. gcepperti with Nothomyrmica rudis 
I. gcepperti with I. geinitzi 
I. goepperti with Lasius schiefferdeckeri 
I. gcepperti with Dimorphomyrmex annectens 
I. gcepperti with Formica flori 
I. schiefferdeckeri with F. constricta 
F. flori with Camponotus mengei 
F. horrida with Leptothorax gracilis 
I. geinitzi with I. samlandicus . 
We are fully justified, therefore, in concluding that I. gcepperti existed 
at the same time and ranged over the same territory as Dolichoderus 
tertiarius, N. rudis, I. geinitzi, L. schiefferdeckeri, F. flori and Dimor- 
phomyrmex annectens. But, strictly speaking, this might only indicate 
that I. goepperti was a very abundant form, spread over the whole 
amber area and persisting throughout its whole duration. It is still 
possible to suppose that the other species enumerated above may each 
have had a more limited distribution in space and time. In other 
words, F. fori, C. mengei , L. schiefferdeckeri may have occurred only 
at high altitudes, forms like Sima, Dimorphomyrmex, (Ecophylla, Dryo- 
myrmex, Prionomyrmex, etc., may have lived only in the low jungles, 
while I. goepperti was much more eurythermal and therefore ubiquitous. 
Such a distribution would be much like that of the present day ants 
in such mountanous portions of the tropics as Mexico and Central 
America. Nevertheless, the view that the tropical and boreal com- 
ponents of the amber ant-fauna belonged to different periods of the 
Oligocene and did not coexist at different altitudes or latitudes is 
clearly favored by the fact that in individual representation the boreal 
are so greatly in excess of the tropical species. This is just what we 
