136 



ZOOLOGY 



of the capsule, and lie in its lumen. The cavity of the capsule 

 also contains certain amoeboid corpuscles, and probably repre- 



FlQ. 86. — Hirudo medicincdis, opened along the 

 median dorsal line, slightly diagrammatic. A. G. 

 Bourne. 



1. Cerebral ganglion. 



2. Oesophagus. 



3. 1st postoral ganglion. 



4. Penis. 



5. Epididymis. 



6. Ovisacs. 



7. Glandular enlargementjof the oviducts. 



8. Vas deferens. 



9. 2nd pair of testes. 



10. Lateral vessel. 



11. 9th pair of nephridia. 



12. Vesicle near external opening of nephridium. 



13. 23rd ganglion. 



14. Posterior sucker. 



sents part of the coelom. The oviducts unite and pass into 

 a muscular vagina, their walls are glandular, and secrete an 

 albuminous fluid in which the eggs float in the cocoon. 



The segments on which the reproductive organs open form 

 the clitellum, which consists of certain segments with glandular 

 walls, the secretion of which hardens and forms in most forms 

 a cocoon in which the fertilised eggs mature. In Clepdne the 

 eggs are attached to some foreign substance, and the female 

 sits over them till they hatch, and then they attach them- 



