240 



PHYLUM ANNELIDA. 



pockets point more or less backwards, it is evident that a 

 leech to be emptied of the blood which it has sucked must 

 be pressed from behind forwards. The pockets filled, the 



leech drops off its victim, 

 seeks to retire into more 

 private life, and digests 

 at leisure. The digestion 

 does not take place in the 

 pockets, but in a small area 

 just above the beginning 

 of the terminal part or rec- 

 tum. This rectum, running 

 between the two last 

 pockets, is separable from 

 the true stomach just 

 mentioned by a closing or 

 sphincter muscle. It ends 

 in a dorsal anus above the 

 hind sucker. 



Vascular system. Two 

 main lateral vessels run 

 longitudinally, one on each 

 side of the body. They 

 are connected with one 

 another by looping vessels, 

 give off numerous branches 

 which riddle the spongy 

 body, and have a definite 

 muscular coat. On the 

 dorsal surface and vent- 

 rally around the nerve-cord 

 are two lacunar spaces, 

 which are really portions 



FIG. 124. Dissection of leech. 

 After Bourne. 



e.g., Cerebral ganglia ; /., penis; s.v. 

 is opposite the seminal vesicle; ov.^ 

 ovary; ut., uterus; v.d.^ vas de- 

 ferens; l.b.v., lateral blood vessel 

 T.4, fourth tesiis ; n.v., nephridia 

 vesicle: -A 7 ". 17, last nephridium 

 6.19, nineteenth pair of ganglia 

 n.c. t nerve-cord. 



n.c 



