146 



ZOOLOGY 



each segment is found, and has been described by Beddard, 

 Spencer, and others. Perichaeta asperffillum has a nephridial 

 network of fine tubules which permeates the body. It is 

 doubtful if any internal funnels opening into the coelom exist 

 in the anterior segments, but they do in the posterior half of 

 the body, and here they are very numerous. On the other 



Fio. 92. — Diagrammatic transverse section through one of the posterior segments 

 of Lumbricns. Partly after Marshall and Hurst. 



On the left side are indicated the chief vessels given off from the main trunk to 

 the body-wall and nephridium. After Beddard. 



hand there are numerous openings to the exterior, both an- 

 teriorly and posteriorly. This network is continuous, and 

 shows no trace of segmentation. In P. armata there is a 

 similar network of fine tubules, but in addition there is in each 

 segment a pair of large nephridia which pierce the septum in 



