FOSSIL ANTS. 



163 



much larger and heavier abdomen, fell into the water more often than 

 the males." The fossil ants of Florissant show the same peculiarities, 

 except that the males are not much rarer than the females. Thus the 

 condition which Le Conte interpreted as indicating an absence of the 

 worker caste during Miocene and premiocene times, is easily and 

 naturally explained. It is strange that he failed to see this, especially as 

 in the paragraph immediately preceding the remark above quoted, he 

 calls attention to the following interesting resemblance between modern 



FIG. 92. Male of Acromyrma 

 sp. from the Baltic Amber. (Ori- 

 ginal.) 



FIG. 93. Worker of 

 Propodomyrma sanilou- 

 dica sp. nov. from the 

 Baltic Amber. (Ori- 

 ginal.) 



lacustrine conditions and those which must have prevailed at Oeningen : 

 " On Lake Superior, at Eagle Harbor, in the summer of 1844, we 

 saw the white sands of the beach blackened with the bodies of insects 

 of many species, but mostly beetles, cast ashore. As many species 

 were here collected in a few days, by Dr. J. L. Le Conte, as could have 

 been collected in as many months in any other place. The insects seem 

 to have flown over the surface of the lake; to have been beaten down 

 by winds and drowned, and then slowly carried shoreward and accu- 

 mulated in this harbor, and finally cast ashore by winds and waves. 

 Doubtless at Oeningen, in Miocene times, there was an extensive lake 

 surrounded by dense forests ; and the insects drowned in its waters, 

 and the leaves strewed by winds on its surface, were cast ashore by 

 its waves." 



The conditions described by Le Conte for Lake Superior are com- 

 mon to all our Great Lakes. The insects drowned in them are often 

 buried in the sand of the beaches and might eventually fossilize, but 



