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THE BOOK OF NATURE STUDY 



Two other water-bugs may be mentioned the two insects 

 to which the name of water-scorpion is applied. The commoner 

 form, Nepa cinerea, is frequent in ponds, where it crawls over 

 the bottom, and is often missed on account of its close resemblance 



to a withered leaf. Its body is flat 

 and of a dull brownish colour, but the 

 most interesting peculiarity is the 

 nature of the fore-legs. These are ex- 

 clusively organs of prehension, and are 

 carried bent on themselves, so as to 

 offer some resemblance to the grasping 

 claws of the scorpion. The two other 

 pairs of legs are used for walking. The 

 water-scorpion breathes by two slender 

 thread-like appendages which protrude from the tail region. It is 

 sluggish in habit, lurking about near the bottom until some un- 

 suspicious larvae, deceived by the leaf-like appearance, ap- 

 proaches within reach. The prehensile fore-limbs are then 

 suddenly straightened, the prey seized and sucked dry. The 

 other form, Ranatra linearis, has a long slender body, stick-like 

 in appearance, long slender legs, and long breathing filaments. 



FIG. 58. The water-scorpion, 

 with fore-legs extended. 



FlG. 59. Ranatra linearis. 



It is more active than its congener, walking about on its stilt- 

 like limbs, and seizing its prey in the same fashion with the rap- 

 torial fore-limbs. 



Leaving the insects, we may mention in passing the interest- 

 ing water-spider (Argyroneta aquatica), always a favourite with 

 aquarium-keepers. As a spider, and therefore an Arachnid, 

 it may be readily distinguished from an insect by having four 



