WHITE ANTS AND DRAGONFLIES. 23 



larvae pass to seek for food. Their soft bodies are so ill-defended 

 that they cannot escape the numerous predacious insects if they 

 venture outside their covered passages*. The winged males 

 and females issue at certain seasons in enormous swarms into 

 the open air ; and these for the most part become the prey of 

 their numerous enemies. In the neighbourhood of rivers and 

 lakes many of them get drowned ; and that this was the case in 

 CEningian times is proved by the winged Termites which the 

 rocks at OEningen enclose. No doubt their mode of life was 

 similar to that of their existing relatives. The two small species 

 probably established their dwellings in the trunks of the Conifers 

 which were so abundant in the CEningian forest ; whilst the two 

 larger ones no doubt built conical edifices, like those inhabited 

 by the tropical species. 



The dragonflies (Libellulina) of CEningen consist of three 

 genera and twenty species. Their larvse no doubt lived in the 

 water, and the adult animals in the air. Of all the three genera 

 both larvse and perfect insects remain ; of the genus Agrion 

 only one species has come down to us in the young state, and 

 of this merely a single specimen, whilst the adults are found of 

 six species. Only three species of Libellula are known from 

 winged specimens, whilst eight are found as larvse. The largest 

 species (Libellula Calypso, Heer) is represented in fig. 232 ; but 

 two other species (L. Doris, Heer, fig. 231, and L. Eurynome, 

 Heer) are much more plentiful, and are the commonest insects 

 at CEningen. They so closely resemble the larvse of an existing 

 species (L. depressa, Linn.) that the adult must also correspond 

 to this, and therefore might easily be referred to the larva in 

 case of its being found at CEningen. Its absence is the more 

 remarkable as the female must have come upon the water for 

 the purpose of depositing her eggs, and must consequently have 

 been in danger of drowning. It must, however, be taken into 

 consideration that the larvse of Agrion live chiefly in running 



* Iii Madeira Prof. Heer shut up a great number of larvse and soldiers in a 

 tin box, in order to observe their development and mode of life. But the 

 little house-ants speedily smelt them out, made their way through the nar- 

 row crevice round the lid into the box, and attacked the Termites. Although 

 the latter were much the larger, they were easily overcome and devoured by 

 the house-ants. 



