216 OKIGIN OF LIFE IN AMERICA 



Columbia, the third in the north-east.* Honey-ants, at least 

 certain members of their colonies, possess the faculty of 

 storing quantities of honey within their bodies, which swell 

 up to a great size, and on that account are somewhat remark- 

 able objects. In North America two species of honey-ants 

 occur, namely, Myrmeocystus melliger and M. mexicanus, 

 both being confined to Mexico, Arizona and the neighbouring 

 regions. The other species of the genus Myrmeocystus in- 

 habit the Mediterranean Region and further east as far as 

 central Asia.f In southern Europe a soft, velvety ant is 

 found belonging to the genus Liometopum. The same species 

 was likewise supposed to inhabit California, but Professor 

 Wheeler J found that although the two forms are very 

 closely related, the American differs slightly in shape and 

 even in its habits from the European species. Whereas the 

 former constructs its nests underground, the latter utilises 

 for that purpose the abandoned burrows of beetles under the 

 bark of trees. Hence he calls the American ant, Liometopum 

 apiculatum. It is limited in its range to California and 

 Mexico. Only two other species of Liometopum are known. 

 One, (L. microcephalum), as I mentioned, lives in southern 

 Europe, the other (L. lindgreeni) in Assam. It is not often 

 that we actually become acquainted with the extinct ancestors 

 of such interesting invertebrates as these. But fossil forms 

 of Liometopum have been discovered, according to Dr. Hand- 

 lirsch in the Lower Miocene of Croatia and the Oligocene of 

 Colorado. Even in Tertiary times the genus seems to have 

 occupied much the same localities as it does to-day ; it only 

 spread formerly further north no doubt owing to the more 

 favourable climatic conditions then prevailing. 



Many other similar instances might be quoted. I will only 

 allude to one more. The two well-known European ants 

 Formica cinerea and Formica rufibarbis had been reported 

 from the south-western States of North America, but Pro- 

 fessor Emery doubted the correctness of the identification 

 until Professor Wheeler sent him American specimens. Both 



* Emery, C., " Nordamerikanische Ameisenfauna," p. 299. 

 t Wheeler, W. M., "Honey Ants," p. 347. 

 J Wheeler, W. M., " North American Liometopum," p. 321. 

 Handlirsch, A., " Die Fossilen Insekten," p. 870. 



