THE WATEE-SCORPION. 585 



• The insecti is common in some places, and can be taken in 

 company with tlie Notonecta as it darts through the water. 

 I have taken great numbers of them in the Swindon Reservoir, 

 and, as far as I know, all my specimens were taken in that spot. 



The next family is that of the Nepid^, popularly known as 

 Water-Scorpions, of which we have but three British examples. 

 The best known of these insects is the common Water- 

 ScoRPiON, which is shown on Plate XIX. Fig. 3. Its scientific 

 name is Nepa cinerea. The Nepidse may be easily known by 

 the flat and leaf-like body and the shape of the first pair of 

 legs, which are formed for seizing prey, their joints doubling 

 upon each other as the blade of a clasp-knife is doubled into 

 its handle. The other two pairs of legs are formed for walking. 



In some of the species, the end of the tail is furnished 

 with two long, slender, bristle-like filaments, which look very 

 much like an apjaaratus of offence. They are, however, adjuncts 

 to the respiratory system, and serve to conduct the air to the 

 spiracles while the body is submerged. In these insects the 

 spiracles are placed quite at the end of the body, those of the 

 sides being only indicated by rudimentary marks. ' In the 

 larval state these filaments are represented by a single sharp 

 point. 



Unlike the quick, dashing, and wary Water-boatman, it is a 

 slow, crawling, inactive insect, and, if seen creeping among 

 the plants near the water side, can be picked up with the 

 fingers ; indeed, it is so very sluggish in its movements that, 

 as it is predacious in its habits, and depends for its food on 

 the capture of other inhabitants of the water, it seems hardly 

 capable of gaining a subsistence. There is, however, but little 

 difficulty in this respect. The Water-scorpion lies quietly 

 among the aquatic plants until some luckless insect comes by, 

 when, with a rapid clutch of its fore-legs, the victim is 

 captured, and held tightly until its juices have been extracted. 

 When in the water, the insect looks so exactly like a small 

 dead leaf, that the quickest eye might fail to discern it as long 

 as it did not move. It is probably on account of this re- 

 semblance to a leaf that the Water-scorpion is able to secure 

 its prey, which consists mostly of the larvae of aquatic insects, 

 such as the Mayfly and Whirlwig beetle. 



