200 



THE HARMONIES OF NATURE. 



a Water-beetle. 

 6 Boat-fly. 



increased. A great development of thigh gives the move- 

 ments the necessary force, and the 

 broad, flat, sharply-margined body is 

 well adapted for cleaving the waters 

 with facility. Thus equipped, these 

 voracious insects, resting motionless 

 on the surface of the water with their 

 heads downwards, in order to watch 

 for their prey beneath, dart down 

 upon it with surprising swiftness, and 

 make great havoc not only among other water-insects, but 

 even among the smaller fishes. Their larvaB, distinguished 

 ,by a long shrimplike body, and using their tail as their chief 

 instrument of locomotion, are no less active and voracious 

 than the full-grown insects, so that in both forms the 

 Dytisci are among the most mischievous animals that can infest 

 a fishpond. 



The NotonectidaB, or boat-flies, are no less beautifully formed 

 for rapid progression in the water. They generally swim on 

 their backs, which are shaped like the bottom of a boat ; and 

 the hind-legs, which are thrice as long as the forelegs, have like 

 those of the Dytisci a fringe of bristles along their edge, by which 

 the surface with which they strike the water in swimming is 

 greatly increased. Their eyes are so placed that they 

 are able to see both above and below the surface of the 

 water, so that at the approach of danger they instantly descend 

 and vanish from the sight. Woe to the unfortunate snail or 

 aquatic Oniscus they descry in their excursions, for with the 

 rapidity of lightning they dart upon their victim from a distance 

 of several inches, and kill it almost instantaneously with a 

 venomous sting ! 



Curveting about in every direction, the small whirligigs or 

 Gyrini animate, during a fine summer's day, 

 the surface of quiet waters. 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 graceful 



Whirligig. 



