36 The American: Naturaliet. [Jin 
attended upon a given female; but there can be no doubt that 
the females are exceedingly slow to accept the males, for I saw 
the above maneuver repeated hundreds of times with the same 
result. 
In company with the species just mentioned occurred con- 
siderable numbers of a species of Hygroceleuthus, which I 
have referred to (Kans. Univ. Quarterly, II., 24) as a variety of 
H. crenatus O. S. These were engaged in a similar occupa- 
tion. The male of this species has only plain tarsi, but differs 
from the female in having the antennal joints longer, the first 
two with coarse black hair, and the arista of the third short 
and heavily covered with black pubescence; the face is also 
longer, the wings broader, and the cilia of the tegulæ, instead 
of being coarse and chiefly black, are fine and white. The 
male hovers in the air before the female at a distance of one 
or two inches, occasionally making a slight darting motion 
towards her. In this position the peculiarities of his face an 
antennæ are shown to the best advantage. The breadth of 
the wings is probably of advantage only in facilitating this 
hovering process, and the structure of the tegular cilia may 
possibly be accounted for by supposing that it is simply in 
compensation for the increased growth of wings. This male, 
after hovering a few secends, describes a semi-circle in flight 
and attempts to alight upon the female as in the foregoing 
species, and with the same results. I observed the copulation 
only once, and then did not see the preliminaries. 
I was much impressed by the perfect coincidence of these 
‘observations with Darwin’s theory of sexual selection. The 
reluctance of the females, and the corresponding ardor and 
persistence of the males, is carried to an almost incredible 
In this connection the observations of Fr. Dahl (Zool. 
Anzeig., April, 1889) on another species of Dolichopus are of 
interest. I translate from a quotation in an article by Dr. 
W. M. Wheeler (Proc. Wis. Nat. Hist. Soc., April, 1889, p. 
209), which mentions a somewhat similar habit in a gall-gnat 
Asynapta antennarize Wheeler). - 
“ The male species of fly, Dolichopus plumipes posseses on 
first tarsal joint of the middle legs a beautiful, regular fringe, 
