FOSSIL ANTS. 



169 



elegant amber sarcophagi, could be carried long distances without 

 sustaining the slightest injury and could, therefore, present this excep- 

 tional appearance, which is seen nowhere else in the plants and animals 

 of the ancient world. If we suppose that a river flowed down from the 

 Sweden of that day and opened into the Tertiary sea near Dantzig, 

 there would be nothing irrational in admitting that this stream might 

 easily carry the amber in the resinous state from the distant localities 

 and mountains of Sweden, so that the organic remains enclosed in the 

 amber may have been gathered together from an extensive territory, 

 from low as well as from mountainous countries, and may even belong 



FIG. 97. 



Worker of Cataitlacus silvestrii from the Sicilian Amber. (Emery.) 

 From the right side ; b, from above ; r, head from above. 



to different Tertiary periods. ... If we admit that the amber does not 

 belong to one and the same epoch, we can explain why in the plants 

 and animals of this formation the mixture of northern and southern 

 types is so much more striking than it is in the remainder of the 

 European Tertiary, and why among these we find several types peculiar 

 to high latitudes or even to mountains." 



At first sight Heer's assumptions are plausible and would seem to 

 be supported by the fact that although ants of different genera are 

 occasionally found enclosed in the same block of amber, these never, 

 to my knowledge, belong to both arctic and tropical types. On the 

 other hand, the fact that the tropical, like the extinct genera of the 



