THE LARVA. 19 



these they are able to capture and devour, not only other 

 insects, but even tadpoles and little fishes. 



Upper Jaws [or Mandlhidm). — These are varied in form 

 according to the kind of food tlic larvf© are intended to 

 live on, but are always hard and horny, and serve such 

 purposes as cutting or grinding the food. Their form in 

 all the caterpillars is that of two slightly concave, oblong, 

 or triangular plates ; the lower extremity being often of 

 irregular form and of considerable thickness, and filled 

 w^ith powerful muscles which move them transversely 

 from the sides of the mouth. The other extremities are 

 divided into two or more teeth, and are made to work 

 against each other, like a pair of pincers. 



In the larva3 of the Capricorn beetles, and other wood- 

 boring species, they are shaped like half a cone, the inner 

 sides of which, applying close to each other, form a power- 

 ful pair of grindstones, capable of grinding the hardest 

 timber. In many, their jaws form a kind of piercing in- 

 strument and sucking tube ; in some even they are used 

 for the purposes of walking or dragging the body along. 

 Some, however, as the common house-fly, .have but one 

 mandible, while a few others have no perceptible mandi- 

 bles of any kind. 



Uncler-Jaws {Maxillm). — These are placed immediately 

 under the upper jaws, are of a softer structure, and do 

 not liave any action upon each other ; they are rather in- 

 tended to assist in placing and keeping the food between 

 the upper jaws — somewhat as is done by the tongue 

 among the vertebrated animals. 



Feelers [Palpi). — The palpi are little conical spine- 

 shaped or jointed feelers, placed either on the under jaws 



