1873. 79 



of the first joint of the hind tarsus are provided with what may bo 

 called comb or rake hairs ; these are shorter and stiffer than the 

 swimming hairs, and are widened and flattened at the extremity, being, 

 in fact, somewhat oar-shaped, and truncate at the apex, which has fine, 

 long teeth. These teeth are admirably adapted to rake out any par- 

 ticles of foreign matter which may have lodged in the fine rastration 

 with which the prouotum and elytra of many species are sculptured ; 

 the species, however, which have no rastration (such as Macrocorixd) 

 are, equally with the rastrate species, provided with rake hairs. These 

 rake hairs are not present in the young. 



The middle pair of legs are used for standing on, the long claws 

 clasping stones or plants, and the body of the animal remaining at 

 some distance from the object rested on. The animal can also walk 

 in a kind of way with these legs, its progress being at the same time 

 assisted by short, jerking strokes of the hind legs through the water. 

 When at rest, and not clasping anything with the claws, the animal 

 rises slowly to the surface of the water. The front legs or palae are 

 used for feeding. When in action, they are brought rapidly and 

 alternately to the rostrum ; in inaction, they hang downwards and 

 inwards, their tips approaching each other ; in swimming, they lie 

 backwards along the sternum. I have not been able to make out 

 satisfactorily of what the food of these insects consists (Westwood has 

 recently described an Indian sjoecies, which is said to feed on the eggs of 

 fish*) . They often rest on a stone, and seem to scrape its surface with 

 the palse, which they bring rapidly and alternately to the mouth. In the 

 same manner they scrape a root of Lemna, passing it rapidly between 

 the palae. On examining a stone from which a Corixa had apparently 

 been obtaining food, a small Alga, and a few Rotifera and other ani- 

 malcules were seen. 



CorixcB generally remain near the bottom of the water, and seldom 

 come to the surface to breathe, as they can carry a large supj^ly of air 

 with them. Air is carried under the hind margin of the head, under 

 the hind margin of the pronotum, in the marginal channel of the 

 elytra, in the short channel between the clavus and corium, on the 

 sternum and under-side of the hind-body, and between the wings and 

 upper surface of the hind-body, being retained in the latter situation by 

 the long hairs at the end of the hind-body. I am not sure, but that, 

 in brushing the elytra with the hind legs, they carry air from the 

 channels of the elytra to the hind-body. 



These insects are not often seen on the wing, probably for the 



* Corixa ovivora, Proc. Ent. 8oc. Loud., 1871, p. iv, Mudi-as. 



