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 gcopperti with Dolichoderus tertiarius 

 I. goepperti with Kothomyrmica rudis 

 I. goepperti with /. geinitzi 

 I. goepperti with Lasiiis schiefferdeckeri 

 I. gwpperti with Dimorpliomyrmex annectens 

 I. goepperti with Formica fieri 

 . I. schiefferdeckeri with F. constricta 

 F. fiori with Camponotus mengei 

 F. horrida with Leptothorax gracilis 

 I. geinitzi with I. samlandicus. 



We are fully justified, therefore, in concluding that I. goepperti existed 

 at the same time and ranged over the same territory as Dolichoderus 

 tertiarius, N. rudis, I. geinitzi, L. schiefferdeckeri, F. fiori and Dimor- 

 phomyrmex annectens. But, strictly speaking, this might only indicate 

 that /. 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. fiori, C. >nengei, L. schiefferdeckeri may have occurred only 

 at high altitudes, forms like ISima, Dimorphomyrmex, Q^copJii/Ua, 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 



