812 THE AMERICAN NATURALIST. 
Wiener Entomologische Zeitung, Vol. XIII, pp. 271-284, and 
Pl. II, Figs. 8-13, gives an exhaustive discussion of the whole 
subject, with citations of the other authors and extracts from 
their papers. According to Mik, who had abundant opportuni- 
ties for observation, the male produces a real web which is 
borne by the hind feet and serves to assist the fly in the some- 
what peculiar gyrations of its flight. The different nature of 
the structure makes it unnecessary to go into further particu- 
lars here. 
The species to which our observations pertain was sent to 
Professor Wheeler, of Chicago, who has been studying the 
family for several years, and identified by him as Empis 
poplitea Loew, “or a closely related species.” 
The use of the term “balloon”’ should not be taken to imply 
that the structure described is lighter than air. 
