18 THE LAEYA. 



wliicli in some, resemble the forms of those in the adult 

 insect, while in others they widely vary. 



The nioutli of the larva, situated in the head, has to 

 answer the purposes, not merely of gathering and chew- 

 ing the food, but often of instruments of cutting and grasp- 

 ing, boring, digging in the ground, of spinning silk, and 

 sometimes also of walking or dragging the body along. 



Upper Lqy {Lahrum). — The mouth of nearly all the 

 larvae is provided with a distinct upper lip for grasping 

 and holding the food while it is being chewed. It is in 

 general a moveable transverse plate fastened behind, or 

 posteriorly, to a part of the head called the nasus, and 

 situated just above tiie upper jaws ; some of the two- 

 winged insects or diptera, however, are without this ap- 

 pendage. 



Under Up [Lahhwi). — Between the two under jaws in 

 most insects is a projecting Heshy organ called the under 

 lip. This varies in shape, being in some conical, in others 

 quadrangular, etc. In those larvae which are able to sj)in 

 silk, on each side of the point of the under lip is a little 

 feeler, and between these a slender bag-1 ke organ called 

 the sphincref, out of which the larva draws the silken 

 thread with which it weaves its cocoon when it is about 

 to assume the pupa state. 



One of the most remarkable prehensile instruments in 

 the entire insect world may be seen in the under lip of the 

 various species of dragon-fly (LiheUidina). In other 

 larvse this part is usually small and inconspicuous, and 

 aids merely in gathering and swallowing the food, but 

 among these it is the largest organ of the mouth, and it 

 serves both for seizing and retaining the prey by means of 

 a pair of saw-edged jaws, into which it is divided. "With. 



