80 THE EARTHWORM. 



deferentia ; and median and lateral vesiculae semi- 

 nales. 



a. The vesiculae seminales vary greatly in form and 



size with the season of the year. When fully 

 developed they form conspicuous milk-white or 

 pinkish bodies at the sides of the oesophagus, and 

 overlapping this. 



i. A pair of anterior lateral vesiculae seminales lie 



in segment ix. They are opaque white bodies 

 attached to the posterior wall of the segment, 

 one at each side of the oesophagus. 



Some earthworms have a similar pair in 

 segment x., but these are not developed in 

 Lumbricus. 



ii. Two pairs of posterior lateral vesiculae seminales 



lie in segments xi. and xn. respectively. They 

 are very much larger than the anterior vesiculae, 

 especially at certain seasons, and are attached 

 to the anterior septa of their respective segments 

 somewhat nearer the median plane than the 

 anterior vesiculae. 



iii. A thin-roofed median vesicula seminalis, of 

 considerable size, is situated in each of the 

 segments x. and xi. below the oesophagus, 

 which must be removed to expose them. 

 Within each are a pair of testes and a pair of 

 seminal funnels. With the anterior of these 

 median vesiculae the anterior lateral vesiculae 

 and the first pair of posterior lateral vesiculae 

 communicate. The second pair of posterior 

 lateral vesiculae open in similar fashion into 

 the second median vesicula. 



The median vesiculae are absent in Allo- 

 lobophora. 



b. The testes are two pairs of small flattened digitate 



bodies attached to the septa in front of segments 



