ANNUL AT A. 



Excretory. 



anterior end are specially contractile and form the lateral 



hearts. The dorsal vessel is also contractile. 



The brain lies in the prostomium, with a nerve-ring 



round the pharynx and a double nerve-chai?i 

 Nervous • 



along the ventral surface. The nerve-chain has 



double ganglia in each segment. 



The nephridia are numerous, a pair occurring in nearly 



every segment. They are complex coiled tubes with an 



internal funnel, a coiled excretory part and a 



small bladder or vesicle leading to the exterior. 



The funnel always opens into the coelomic compartment in 



front of the one in which the bulk of the nephridium lies. 



Fig. 128.— A Nephridium of Lumbricus. 



NepJiPQStome. 



First .S 

 Thin- fe 

 walled 

 Portion. 



Respiration appears to l)e carried on by the skin. The 

 worm is hermaphrodite. (The male organs consist of two 



_ ... pairs of testes lying in the loth and nth seg- 

 Reproductive. ^ ^ rj., i j • .u 1 u u 



ments. They are enveloped m the large branch- 

 ing seminal vesicles^ from each of which there passes a vas 

 deferens backwards to open on the 15th segment. The 

 pair of ovaries lie in tBfe 1 3th segment, and the oviducts, with 

 funnels opening into the same segment, run through the 

 septum and open to the exterior on the 14th segment! 



Two pairs of spermathecce. or small spherical sacs open 

 between 9 and 10 and between 10 and 11 on each side. 



The eggs are laid in cocoons and undergo an embryonic 

 development. The cocoons are secreted by the clitellum. 



