SCORPIONS, SPIDERS, MITES. 195 



GLASS II.: MYRIOPODA (CENTIPEDES AND 

 MILLIPEDES). 



Respiration by tracheae, as in insects. The body 

 consists of a head and a large number of very similar 

 segments, each of which possesses limbs. One pair of 

 antennse. 



This class is divided into two orders: (1) that of 

 Centipedes (Ghilopoda), with mouth-parts adapted for 

 seizing prey, and one 

 pair of legs to each 

 segment; (2) that of 

 Millipedes (Chilog- 

 natha), adapted for de- 

 vouring substances re- 

 sembling humus, also 

 the parts of plants ; 

 and two pairs of legs 



to each segment. Here Fig. 123.— common snake Mimpeae 



belong, above all, the C«"» *«-'-.s(r«;. Bomewhat magnified. 



Snake Millipedes (Julus) or "False Wireworms" 

 (Fig. 123), of which several species eat out germi- 

 nating seeds (peas, beans, mangolds, and beet), and 

 also attack juicy plant parts (potatoes, turnips, 

 carrots). Seedlings may be protected by using 

 potatoes to draw away the millipedes. 



CLASS III.: ARACHNOIDEA (SCOEPIONS, 

 SPIDERS, MITES). 



Air-breathing (by ordinary or modified trachese) ; 

 the lower forms breathe with the skin. Body at most 

 consists of two chief regions, since head and thorax 

 are always fused together, making up a cephalothorax 

 (Fig. 124); but this may again be united with the 

 always unsegmented abdomen into a single piece 



