584 INSECTS AT HOME. 



and sharp, and can be used as an instrument of defence at the 

 will of the insect. If the Notonecta be seized carelessly, it 

 will drive its beak into the hand, causing a sharp, smarting 

 pain, which at the moment so closely resembles the sting of a 

 wasp, that few persons can resist the instinctive action of 

 dropping the insect. No real harm, however, can be done, 

 and the pain goes off almost as rapidly as it was caused. 



There are many species of Water-boatman, the insects be- 

 ing arranged in several genera ; but, as the form and habits 

 of them all are very similar, there is no need for further 

 description. • 



An allied group of insects is known by the generic name of 

 Corixa. A magnified view of the commonest of these Water- 

 boatmen is shown on Woodcut LXVIII. Its scientific name 

 is Corixa Geoffroyi. In these insects the scutellum is not 

 visible, because the thorax is prolonged over it. The fore-legs, 

 although they are used for prehensile purposes, are not so 

 entirely raptorial as those of the Notonectse, and the tarsus is 

 composed of a single long pointed joint, fringed on the inner 

 edge with stiff bristles. The middle legs are slender, as are 

 their claws, and the long hind legs have the two tarsal joints 

 fringed, and are used for swimming. The body is much 

 flattened above, and this peculiarity alone is sufficient to dis- 

 tinguish it from the Notonectse, with their boat-like backs. 

 The beak is short but sharp, and can inflict a smart prick on 

 the fingers if incautiously seized. 



Mr. Westwood remarks that in the winter time he has seen 

 great numbers of Corixse huddled together under the ice, most 

 of them grasping each other with their legs. They appeared 

 to be stupified with the cold, and to have no idea of devouring 

 each other. 



The present species is blackish-brown, with a slight yellowish 

 tinge. Upon the upper part of the thorax are a number of 

 small yellowish spots, arranged in transverse rows, and some- 

 times running into each other, so as to produce the effect of 

 delicate, irregular stripes. The head is yellow, and the e3'-es 

 and beak are black. If the elytra be examined with a tolerably 

 powerful magnifying glass, they will be seen to be covered 

 with very fine hairs of a pale yellow tint. 



