CENTIPEDES AND MILLIPEDES 



395 



The most obvious appendages of the head (fig. 244) are two 

 long-jointed antennae, while the remainder consist of three pairs 

 of jaws guarding the opening of the mouth, and overlapped by the 

 poison-claws. There is also a plate-like upper lip. The jaws, 

 which are comparable in some respects to those of a cockroach 

 (see p. 345), consist of a pair of hard-biting mandibles, followed 

 by delicate flattened 

 \st maxillcB, and these 

 again by leg -like 2nd 

 maxilla. 



As in an insect, the 

 breathing organs are 

 air - tubes ramifying 

 throughout the body, 

 opening to the exterior 

 on the sides by small 

 holes (stigmata), of 

 which the 3rd, 5 th, 8th, 

 loth, 1 2 th, and 14th 

 leg - bearing segments 

 each bears a pair. A 

 group of simple eyes is 

 to be seen on each side 

 of the top of the head. 



It will be seen from 

 the above description 

 that a Myriapod is de- 

 cidedly simpler in struc- 

 ture than an Insect or 



average Arachnid, only the front part being clearly marked off as 

 a head, while there is no distinction between thorax and abdomen, 

 though the first segment of the trunk is specialized. The presence 

 of numerous pairs of legs, extending right to the posterior end of 

 the body, is also characteristic, there being no restriction of walk- 

 ing-legs to the front part of the trunk, as in a scorpion or cock- 

 roach, where there are no legs on the abdominal region. As in 

 many other cases of animals with unspecialized trunk, there is 

 considerable variation within the limits of the class as to the 

 number of segments, and another noteworthy point is the similarity 

 these segments exhibit among one another. 



Fig. 244. — Structure of Centipede 



i, Mandibles ; 2, Brst maxillas; 3, second maxillae; 4, first limbs of 

 trunk, with poison claws 



