144 Mr. J. W. Dunning on 



But it will be said there are other differences ; and 

 Brown describes the apterous female as being furnished 

 *' with long silky white fringes to its hinder tibiae," from 

 which he presumes it '' to be endowed with active swim- 

 ming and diving powers/^ But a reference to Brown's 

 figures shows that the winged female has the tibial fringes 

 as strongly developed as the wingless female, and that, 

 so far, she is equally well endowed with swimming and 

 diving powers, unless her wings act as impediment. As 

 to this, I may recall Lubbock's exhibition of Polynema 

 fuscipes, swimming by means of its wings (Proc. Ent. 

 Soc. 1862, p. 93), a Hymenopterous insect with large 

 fore-wings profusely fringed all round, whose motion 

 through the water is due entirely to a sharp jerking 

 action of the wings : and, to return to Acentropus, I have 

 already suggested that the female which Kolenati saw 

 descend into the water in 1846 must have been a winged 

 female ; but, however this may have been, it is abundantly 

 clear, that the winged male can exist under water ; and 

 if the winged male, why not the winged female ? if the 

 winged male deliberately descends into the water in pur- 

 suit of the apterous female, why not also in pursuit of the 

 winged female? With reference to these tibial fringes, 

 I may mention, that not a trace of them was to be seen 

 on the (winged) specimens which first came under my 

 examination; I thought, therefore, that they might be 

 confined to the apterous female, and that there might 

 have been an error in Brown's figure of the winged female 

 (figs. 7,9). But in reply to enquiries. Brown informs 

 me that a winged female from London, now in his collec- 

 tion, " has the brushes at the present moment of full size 

 as depicted." And I have since had the pleasure of 

 seeing winged females from Cheshunt, which exhibit 

 traces of the fringe, and a continental female of ^. lati- 

 pennis which shows it quite prominently.* It seems clear, 

 then, that like the leg spurs of the male, these fringes 

 are easily deciduous : but if so, how about their use in 

 swimming ? 



I pass on now to A. Nevce, of which I have seen speci- 

 mens given by Nolcken to Stainton. Judging from 



* Nolcken thouglit he saw a trace of the fringes on a male from Stral- 

 Bund ; but he could not feel certain about this. 



