CHAPTER III. 

 BRANCH ARTHROPODA. 



CLASS MYRIAPODA. 



Myriapoda. The myriapods ("thousand legs" and cen- 

 tipeds) have a wormlike form, but, like other Arthropods, 

 have a more or less hardened external skeleton, and possess 

 jointed appendages. The head is distinct, but after it the 

 segments are alike, there being no distinction of thorax 

 and abdomen. On the sides or ventral surface of most of 

 the segments are the spiracles or breathing pores, which 

 lead to the air tubes, or tracheae, as in the insects. 



FIG. 38. CENTli'ED. 



The head, as in insects, appears to be composed of sev- 

 eral segments, fused together; it bears a pair of many- 

 jointed antennas, a pair of eyes, and two or three pairs 

 of jaws. 



There are two principal groups, the centipeds and the 

 millipeds. The centipeds have flattened bodies, with one 

 pair of legs to each segment. They are carnivorous, and 

 have a poison gland opening at the tips of the first pair of 

 legs, which act with the mouth parts. The millipeds, or 

 thousand legs, have cylindrical bodies, and may be recog- 



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