A CENTIPED 21 



of maxillae, the second pair of which is homologous to the 

 labium of insects. 



Exercise 3. Remove, under a dissecting microscope, the prehen- 

 sile hooks and the mouth-parts, beginning with the pos- 

 terior ones and working forward, and the antennae. Mount 

 them on a slide and draw an outline of each. Compare 

 the different structures of the mouth-parts with those 

 of the insect and label them all. 



The internal organs. The digestive, circulatory, respiratory, 

 excretory, and nervous systems are essentially like the same 

 systems in insects. The reproductive system consists of a 

 pair of sexual glands with paired ducts, the posterior portions 

 of which unite to form a common duct. This opens to the 

 outside in the genital segment, which is the penultimate body 

 segment. 



