OR WATER-BUGS. 407 



that the Notonecta is capable of inflicting a severe 

 wound upon the fingers when captured. 



The species of the genus Corixa, which is nearly 

 allied to the preceding, are still more abundant than 

 the common Boat-fly, and we can scarcely fail to see 

 them swimming in every piece of water, however 

 small. In their habits they are very similar, except 

 that they swim with their backs upwards, and I have 

 seen them flying in great abundance over the water 

 in fine bright days in spring, which, I believe, is not 

 a practice with the Notonecta. 



In the preceding insects, but especially in the 

 Corixa, the anterior legs have more or less of a rap- 

 torial character, but in the remainder of this tribe 

 this is very strikingly the case. In all these insects 

 the anterior coxse are of large size and possess great 

 freedom of motion, and the thighs are exceedingly 

 thick. The tibiae, usually terminated by one- or two- 

 jointed tarsi, form slightly curved organs, which close 

 down upon the thickened thighs, like the blade of a 

 knife upon its handle, and thus form an admirable 

 instrument for seizing prey. Of the British species 

 which exhibit this structure, two are furnished with 

 a pair of long bristles at the tail, which, when applied 

 together, form a sort of tube leading down to the 

 only effective spiracles in the creature's body. The 

 insect, applying the tip of this tube to the surface of 

 the water, respires in this position, and the commonest 

 species, usually known as the Water Scorpion (Nepa 

 cinerea), may often be seen thus engaged. It is a 

 dull, brownish-grey, flat, elliptical insect, nearly an 

 inch in length, with the sides of the back of the 

 abdomen, underneath the wings, bright red. Its pos- 

 terior and intermediate legs are slender, and its move- 



