INSECTS 41 



prominent eyes keep careful watch. The water-boatman has 

 a very low specific gravity, and therefore must cling on to 

 weeds or sticks in order to remain below. Sometimes the little 

 creature will be seen to dart down into the mud, and often 

 seizing a quantity rise through the water for a moment, and 

 then after dropping the mud dart down again. This behaviour 

 may be repeated for some time. Notonecta is not feeding, nor 

 is it attempting to alter the bed of the pond, but the fact is 

 that it wished to remain below, and seizing some loose or light 

 matter of low specific gravity rises with it. For a moment the 

 water-boatman does not realise that it is rising, but on doing 

 so wastes little time in throwing away the encumbrance. 



At intervals, when its air supply is exhausted, Notonecta rises 

 to the surface, and extrudes its abdomen. Sometimes on 

 reaching the water-film the little creature will actually walk 

 on the underside without breaking it in a most curious manner. 

 On fine days it will rest just beneath the water-film, as if en- 

 joying the warmth of the sun. 



The boatman seizes its prey with its front legs, and holding 

 it thus above it sucks out its juices by means of its sharp beak 

 until nothing but the skin and solid parts remain. 



This sharp beak the creature is an adept master of, as the 

 following incident will show. 



An ardent pond-hunter on one memorable occasion placed a 

 matchbox containing a large water-boatman in his pocket. 

 Later, having to resort to his handkerchief, he placed his hand 

 in his pocket. But Notonecta, which had escaped from the 

 matchbox, probably mistaking the action, " pinched " him. The 

 sudden pain was too much for the pond-hunter's feelings or 

 language. In a moment off came his coat and out came Mr. 

 Notonecta. 



The Corixidae are often mistaken by the novice for Noton- 

 ecta, but it can easily be seen that they only bear a very casual 

 likeness to each other. The adults are brown or green marked 

 with yellow spots. The back is flat, not keeled as in Noton- 

 ecta, and Corixa swims back uppermost. The female lays her 

 eggs singly on water-plants. The young hatch into queer little 

 creatures very similar in appearance to their parents, except 

 that the wings are only rudimentary. 



Like Notonecta, Corixa is exceedingly savage. The female, 

 some eight days after conjugation, lays her eggs, which are 

 brown cased structures in shape resembling turnips, and each 

 one is fastened separately by a minute stalk to the stem of a 

 weed : gradually these eggs become more swollen, until four 

 weeks later the top of the case cleaves open, and the young 



