March, 191/.] HUNGERFORD : FoOD HabITS OF CoRIXIDS. 3 



material containing threads of Zygnema, diatoms, spores, euglenae, 

 etc. Amongst this material plows the little Corixid, leaving in its 

 wake a ridge of sediment bounded upon either side by a furrow. 

 The body is supported upon the long middle legs. These legs are 

 broadly spread. The femora go out at right angles to the body, the 

 tibia turn down at a wide angle, thus providing a biped support upon 

 which Corixa swings from the horizontal to a position with the face 

 nearly parallel to the surface of the leaf, and the caudal end of the 

 body elevated. This support suits Corixa's purpose, for it moves 

 forward in feeding rather slowly considering the rapidity of its other 

 movements. When an advance position is desired, first one leg is 

 brought forward and then another, rather stiffly, like a boy on stilts. 

 The arc of this swing enables it to bring the face against any mass 

 of this loose material and working the forelegs rapidly it gathers 

 double arm loads of material and passes it across its face from front 

 to rear. Arm load after arm load passes by its face, appressed there 

 by the flat rakes of its forelegs (Plate II, fig. 5). The buccal open- 

 ing is on the cephalic surface of the beak and thus this machine, 

 doubtless working like a colander, sends into the mouth bits of food 

 material, and that which passes by is crowded on under the body be- 

 tween the middle legs and soon appears from beneath it partly due to 

 the Corixid's advance and partly to the force of the material crowded 

 after it. 



The hind legs are all the while out at an angle to the body after 

 the fashion of the parent and now and again strike forth in one or a 

 whole series of rapid strokes that propel it forward not at all, but 

 doubtless drive a current of water with its newer air supply across 

 the body. 



So intent is Corixa upon its work of embracing this food-con- 

 taining material that it pays slight attention to the cyclops that scurry 

 by — to the little grayish spotted ostracods that glide in and out of the 

 way, or to a baby snail that comes close. 



Beginning with the third instar, the Corixids evince more concern 

 regarding their air supply, and spend less time in continuous feeding. 

 The adults also are nervous feeders, gathering up a little in one place, 

 then suddenly darting to another, with no apparent reason. 



If one examines the head parts of a Corixid, it will be soon dis- 

 covered that the stylets, when exserted, are directed forward out of 

 the opening which lies on the cephalic side of the beak a trifle above 



