118 ANNELIDA 



2. The ventral blood vessel and the lateral branches. 



3. The nephridia, of which there are eighteen pairs. 



4. The male reproductive organs. On the midventral line 

 ventral to the nerve cord, and opposite the external opening 

 already observed, is the globular muscular penis. Just an- 

 terior and laterally are a pair of white seminal vesicles. A 

 short broad duct leads from each vesicle to the penis and a 

 long narrow duct leads posteriorly to connect with the nine 

 testes on the same side. The anterior pair of testes are four 

 somites behind the penis and the eight others are in the suc- 

 ceeding somites. The testes are rounded white organs near 

 the nerve cord. 



5. The female reproductive organs which lie behind the 

 penis. The vagina is a muscular sac on the median line op- 

 posite the opening already described. From the anterior 

 dorsal side the oviducts run to the two small white ovaries, 

 which are near the vagina, but a little anterior and lateral 



to it. 



6. Four mucous glands, behind the vagina and opposite 

 the openings on the ventral side. 



Draw. 



Nervous System. — The location of the ventral cord has 

 already been noticed. 



(a) How many ganglia? 



(b) Are the ganglia of equal size? Do they all give off 

 the same number of lateral nerves? 



(c) Find the supra- esophageal ganglia, above the pharynx. 



(d) Observe the connectives that join the supra-esopha- 

 geal ganglia to the first pair of the ventral chain, the infra- 

 esophageal ganglia. 



(e) Find the nerves that run from the supra-esophageal 

 ganglia to the eyes. 



(/) There are three stomogastric ganglia, one on each 

 side of the muscular lobes of the buccal pouch and one on 



