1890.] 207 



and each time a (^ has swooped down and carried off the ? before I 

 could capture it. The ? , when intent npon ovipositing, iiies around 

 the lake, and when she sees a suitable place settles down to her work, 

 the wings vibrating and the body being dipped into the water. 



Guisaclmn School House, Beauly : 

 August Uth, 1899. 



AN OBSERVATION ON THE VOLUNTARY SUBMERGENCE OF THE 

 FEMALE OF EN ALL AG MA CYATIIIGERUM, Chp. 



BY ROBERT McLACHLAN, F.R.S., &c. 



On the last day (August 1st) of a recent short visit to the won- 

 derful ancient volcanic district of Auvergne, I joined an excursion 

 party from Clermont Ferrand to the little Lac d' Aydat by vehicle. 

 The distance was long, the route mountainous, the scenery magnificent, 

 the sky cloudless, and the heat great. The distance permitted of only 

 two hours' stay, but some collecting was done, mostly in the way of 

 Af/rionidce, a few species of which (mainly E. cijitthigcrum and Agrion 

 Lindenii and puella) were abundant (^Ischnura elegans and Lestes 

 sponsa were also represented). A weedy patch on the lake (which 

 is the basin of an ancient crater) was exceptionally rich in Agrions, 

 and there were many of them paired in the familiar manner. When 

 watching a pair with a view to capture, the female suddenly dis- 

 engaged herself and rapidly entered the water. I am of opinion that 

 she did not descend the stem of a water plant, but was in the 

 free element. She certainly descended for several (six at least) inches, 

 and the wriggling motion of her abdomen when doing so was con- 

 spicuous. It was impossible to determine whether the wings were 

 used in any way. It has been said that the male awaits the re-appear- 

 ance of his partner in such cases, and that the operation is repeated. 

 In this particular instance the statement could not be verified. The 

 male settled quietly near the spot on a water weed, and being anxious 

 to determine the species a sweep of the net made him captive. In 

 the meantime the female was lost sight of. The point that struck me 

 most was the probability that the submergence was not effected by 

 the aid of a plant, and the wormlike motion of the abdomen below 

 the surface favoured this supposition. This motion was much like 

 that of the free end of a worm on a fish hook, and it occurred to me 

 that the submerged females of AgrionidcB intent on oviposition must 

 form attractive morsels to fish (this particular lake was full of fish), 

 and furnish another instance of the struggle for existence that 

 everywhere obtains. 



Lewisham, London : 



Augud Qlh, 1S99. 



