CHAETOPODA I4I 
of the ventral middle line (Fig. 90). The testes are similarly 
built up from peritoneal cells, situated on both sides of the 
oblique septa, in the segments which succeed the seventh. 
pig) 
wy 
Ht 
Hat 
Fic. 89.—Polygordius neapolitanus. (After Fraipont.) 
A. The living animal. x about 5. D. Portion of body, showing 
B. Anterior end of the worm seen from the 1. Segments separated by grooves. 
right side, more highly magnified. 2. Grooves. 
1. Prostomium. E. Ventral view of posterior end, show- 
2. Peristomium. ing the last three segments. 
3. Tentacle. 1. Segment. 
4, Setae on tentacle, 2. Groove. 
5. Ciliated pit. 3. Anal segment, 
C. Ventral view of the same. Numbers 4, Anus, 
as in B. 5. Ring of papillae. 
6. Mouth. 
Histriodrilus, which lives parasitically upon lobsters’ eggs, 
is somewhat more highly organised than Protodrilus. The 
body is differentiated into regions, the nervous system has 
