530 



ZOOLOGY 



SECT 



duced along its inner edge into strong teeth. The mandibles lit 

 one on each side of the mouth, and are so articulated that, b 

 means of muscles, their toothed edges can be brought together ii 

 the middle line, so as to rend the food. 



The fourth and fifth appendages are very small, and are prob 

 ably functionless or nearly so : they follow one another just behinc 

 the mandible, and are called the first arid second maxillae. Th 

 first maxilla (4) consists of two curved chitinous plates, the secoric 

 of a basal portion produced into two branches (5). Between th( 

 first maxilla and the mandibles are a pair of delicate unjoin tec 



5, 2 nd Maxilla 



fir 



lO.I^AbdominalFool- 



FIG. 423. Typical appendages of ApUB. 1 k, podomeres of axis ; br. bract ; en. 1, en. 7, endites 

 jl. flabellum ; ov. ova. (After Laiikester.) 



processes, the paragnatha (Fig. 421, pgn.}: they form together 

 sort of lower lip, and are not usually reckoned as appendages. 



The foregoing appendages all spring from the unsegmentec 

 anterior portion of the body or head. As we shall see, however 

 the succeeding limbs arise each pair from its own segment, sc 

 that the presence of five pairs of appendages on the head ma) 

 be taken provisionally as an indication that this region of the 

 body is composed of five fused segments. 



The sixth appendage (6") springs from the ventro-lateral region 

 of the first clearly marked segment, and is the first of the long 



visible in a ventral view. It consist:: 



row 



of appendages plainly vi 



of an axis formed of four podomeres (1-4), and bearing a number 

 of offshoots : six of these, called endites (en. 1 en. 6), arise from 



