BIOLOGY AND STRUCTURE OF HYDROPHILUS CARABOIDES 635 



The under-lip (Text-figs. 3, 4, Ih) serves as a plate on which 

 the preparation of the food is effected. During the feeding 

 process the labial palpi (Text-figs. 3, 4, jjU) are all the time in 

 motion. Owing to the work of the mouth-parts the body of 

 the captured animal is kneaded, with the result that the liquid 



Text-figs. 5, 6. 



/7^ 



f-r 



r 



Fig. 5. — Right antenna of newly- hatched larva. The inner edge 

 is serrated ; outer edge simple. Winkler, ob. 1, oc. 2. 



Fig. 6. — Antenna and mandible of mature larva. Inner edge of 

 antenna set with hairs, outer edge bears a row of short spines (a). 

 md, mandible. Winkler, ob. 1, oc. 0. 



parts or those being in a state of emulsion can be sucked up by 

 the larva. 



But into the alimentary system of the larva are introduced 

 also the solid constituent parts of the prey after they have been 

 treated with the ferments of a black digestive fluid which is 

 exgurgitated from the intestine. 



The whole of the feeding of the larva of H. caraboides 

 takes place outside the water, a fact that, as has already been 

 said, depends on the structure of its mandibles, which, in con- 

 trast to those of the larvae of the Dytiscidae, are not pierced 



