ARTHROPODS AND MOLLUSCS 



155 



Millipeds and centipeds (class Myriapoda). The Myria- 

 poda are land-animals breathing by means of trachea? 

 like the insects. In them the body-segments are nearly 

 uniform in character with the exception of the head, which, 

 as in the insects, bears the mouth-parts and antennae. There 

 is no grouping of the body-segments into regions except as 



the head is distinct 



from the rest of the 



body. (In a few 



myriapods there 



are indications of a 



division of the hind 



body into thorax 



and abdomen.) 



The presence of 



true legs on all the 



segments 



of 



the 



hinder region of 

 the body and the 

 lack of the three- 

 division of 

 body are the 



region 



the 



FIG. 64. A galley- principal external 

 worm(miiiiped) structural charac- 



Julus sp. ... i i T 



tenstics which dis- 

 tinguish myriapods from insects. 

 The internal anatomy corresponds 

 in general character with that of 

 insects. 



The most familiar myriapods 

 are the millipeds, and the litho- 

 bians and centipeds. The mil- FIG. 65. 

 lipeds are cylindrical in shape, 

 have two pairs of legs on most of 



The skein centiped, 

 Scutigera forceps, common 

 in houses and conservato- 



ries. 



.^^. (Natural size; after 



the body-segments and are vege- Marlatt.) 



