230 AHhropoda. 



The Scolopendras, of whicli several species are luminous, are 

 active and predaceous, killing tlieir food with the poison-claws. In 

 temperate zones the few species are relatively small; they attain to an 

 important size in the Tropics (to a foot long). In England, there 

 are several species of Lithobius, and others. 



Order 2. Chilognatha or Diplopoda. 



Only two pairs of jaws, generally termed mandibles and maxillae, 

 are present. The structure of the body is very peculiar : whilst the 

 two legs of each pair arise far apart in the Chilopoda, separated by a 

 wide sternal plate, here they are articulated near to one another on 

 the ventral side. Moreover, most segments bear two pairs of legs, 

 indicating that each segment has really arisen by the fusion of two. 

 The four segments following the head have not, however, more than 

 one pair of legs each ; indeed, one of them is altogether apodous. 

 The shape of the segments varies : in some (Fig. 193 B) they are 



Fig. 193. Transverse sections : 4 Of a Chilopod. B — D Of different Diplopoda 

 (JB lulus, D Olomeris), P lateral outgrowth. — Orig. 



cylindrical ; in others each segment is a compressed cylinder, but 

 possesses a short lateral process, which gives the body a more flattened 

 appearance (Fig. 193 G) ; in others, again, the body is itself flattened, 

 convex dorsally and concave ventrally (Fig. 193 D). The legs, 

 which are feeble and thin, are turned out; they are all essentially 

 alike (excepting those which serve in the males as copulatory organs, 

 see above). It has already been stated that the genital apertures are 

 anterior and that copulatory limbs are present. 



The members of this order are sluggish animals, which live on 

 decaying or soft vegetable matter or animal remains. When dis- 

 turbed, they roll themselves together. 



Occurring in England are lulus, with an elongate, cylindrical body; and 

 Glomeris, with short, semi-cylindrical body, composed of so few segments that 

 it bears a superficial resemblance to Armadillidium. 



