122 



HABITS AND INSTINCTS OF ANIMALS. CHAP. IV. 



" each individual rising and falling, in a vertical line, a 

 certain space, and which will follow the passing tra- 

 veller, often intent upon other business, and all uncon- 

 scious of his aerial companions, for a considerable dis- 

 tance." Mr. Kirby further remarks, " that the smallest 

 Tipulidce will fly unwetted in a heavy shower of rain, as 

 I have of ten observed. How keen must be their sight, and 

 how rapid their motions, to enable them to steer between 

 drops bigger than their own bodies, which, if they fell 

 upon them, must dash them to the ground ! " * 



(145.) The little water beetles of the genus Gyrinus 

 (fig. 41.), so frequently seen 

 on the surface of freshwater 

 ponds in a bright summer's 

 day, are as joyous a race as 

 their brethren the gnats. The 

 rapidity with which they skim 

 in undulatory circles is not less 

 admirable than the precision 

 with which they thread the 

 mazes of their aquatic dance, so as never to encounter, and 

 seldom to touch, each other. Their flattened and oar- 

 shaped hind feet are peculiarly 

 adapted for these exercises ; 

 and they continue their diver- 

 sion for hours with unwearied 

 gaiety. They are the only 

 instance of coleopterous insects 

 swimming on the surface of 

 the water; for the Dytiscidce 

 (jig. 40. a), which are preda- 

 cious, merely rest there mo- 

 tionless, with their heads down- 

 wards, in order to watch for 

 their prey beneath. They are, 

 in short, the fissirostral or aquatic type of the predato- 

 rial family (Predatores Sw.), and, like them, dart upon 

 their prey from a fixed station. Some of the hemipte- 



* Int. to. Eni. p. 367. 



