236 PEESH-WATEE AQTTAEIA. 



those of its relatives, and while in confinement it should be 

 treated in the same way. 



The best known, bnt perhaps not the commonest, member 

 of the family Notonectidce is Notonecta glauca (Fig. 149), 

 or Water -Boatman. This curious and interesting insect 

 may very frequently be observed floating upon its back, 

 with its oar-like legs extending at right angles to its 

 body, just below the surface of nearly every pond or 

 ditch. It is a little more than fin. long; its body is convex 

 and slightly keeled above and flat below, and its prevailing 

 colour is yellow, with the exception of a black mark in the 

 shape of a triangle upon the back ; this black triangle is 

 the scuteUum. N. glauca has a broad head, very bold-looking 

 eyes, four-jointed antennae, and the tibia and tarsi of the 



hind-legs very flat and 

 fringed on both sides with 

 a kiad of hair. The crea- 

 ture's fore-legs are raptorial, 

 and its beak is so sharp 

 and strong that it is able 

 to inflict quite a painful 

 wound on the human 

 hand. The eyesight of the 



FIG. U9. Water-Boatman Water-Boatman is very 



(Notonecta gladca). 



acute, and he will dive 



quickly to the bottom of 



the pond or ditch directly his would-be captor puts forth 



his net to take him. This insect looks well in the aquarium, 



for it is very lively and an expert swimmer. It always swims 



upon its back, and as it dives beneath the water it takes 



with it a store of air entangled in the hair with which parts 



of its body are covered. The air under these circumstances 



has somewhat the appearance of quicksilver, and makes the 



insect very attractive as he darts to and fro among the weeds 



of a well-arranged tank. But beauty, activity, and method 



of respiration, are about all that can be said in its favour; 



for it is extremely predaceous, and will quickly attack and 



kill most of the aquatic animals which are usually kept in 



