146 ZOOLOGY 
each segment is found, and has been described by Beddard, 
Spencer, and others. Perichaeta aspergillum 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 
SS 
Sepa, 
SON] \, 
AB AY \} WN ly A 
VZRAAAZY AD 
NAS NGNAINIS BE 
1 
Fic, 92.—Diagrammatic transverse section through one of the posterior segments 
of Lumbricus. Partly after Marshall and Hurst. 
1. Nephridium. 8. Typhlosole. 
2. Funnel of nephridium. 9. Dorsal blood-vessel connected by a 
3. Nerve cord. vertical branch with typhlosole, 
4, Epidermis, and by branches with intestinal 
5. Circular muscles. blood plexus. 
6. Longitudinal muscles. 10. Supraneural vessel. 
7. Dorsal and ventral pairs of setae, 11. Infraneural vessel. 
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 
