64 THE ZOOLOGIST. 
NOTES ON THE WHIRLIGIG BEETLE 
(GYRINUS NATATOR). 
By Gorpon DatlGuiesH. 
Berne one of the commonest of British aquatic beetles, the 
Whirligig is in consequence easy to study in its wild state. 
There is hardly any pond where it may not be found, provided 
the conditions are favourable for its mode of life. Swift running 
water it shuns for reasons which are obvious, but a stream with 
a gentle flow, especially where a back eddy causes pools of clear 
water, it occasionally favours with its presence, though its 
haunt par excellence is a pond free from much surface-covering 
weed, where it can have full scope for its play. Prof. Miall’s 
delineation in comparing its movements to those of Swallows 
and Bats is a happy one, for this exactly portrays its whirling 
performances—those delightful mazy, intricate dances that 
cannot fail to have charmed those who take an interest in water 
*‘ beasts.” To my mind, a number of Whirligigs always bear a 
fanciful resemblance to a flotilla of torpedo-boats, and the 
torpedo shape of Gyrinus fits it exactly for its manner of life. 
If a single Whirligig be picked out and carefully watched, it will 
be seen that it progresses by a series of jerks. This is not so 
noticeable when viewed en masse. THKach beetle, too, is sur- 
rounded by a circular depression about the size of a shilling, 
owing to the tension of its weight on the surface-ilm. Swim- 
ming is seldom performed in a straight line, but in that of 
serpentine curves, and the beetle frequently rotates, so to speak, 
on its own axis. Now and again a pair will waltz round each 
other without coming into actual contact. They frequently 
chase each other, the pursued keeping about its own length 
ahead of the pursuer until finally overtaken, when both execute 
a, téte-a-téte circle. This proceeding is sometimes, though not 
always, the prelude to an amorous embrace. I have seen pair- 
ing take place as early as the middle of March, which is but of 
