STEUCTUEE OF TWO NEW GENEEA OP EAETHWOEMS. 275 



PLATE XVII. 

 Hyperiodrilus africanus and Heliodrilus lagosensis. 



Fig. 13. — Diagrammatic transverse section of Hyperiodrilus in neigh- 

 bourhood of the female reproductive organs, to be compared with 



Fig. 14, representing a corresponding section through Heliodrilus. 



Fig. 15. — Heliodrilus. The sac, containing testis and its attachment 

 to the body-wall. mes. Mesentery. Im. Longitudinal muscle-fibres. 



Fig. 16. — Heliodrilus. Dissection of ccelomic space, containing testis 

 and first part of vas deferens. The wall of the sperm-sac is partly remoyed 

 to show funnel. 



Fig. 17. — Transverse section through alimentary canal (int.) and the 

 dilated part of the vas deferens {v. d.) of Heliodrilus. 



Fig. 18. — Dissection to show male reproductive system of Heliodrilus. 

 ves. sem. Sperm-sacs. a^r. Atrium uncoiled ; on the opposite side it is left 

 coiled up. 



PLATE XVin. 

 Hyperiodrilus africanus and Heliodrilus lagosensis. 



Fig. 19. — Hyperiodrilus. Magnified view of the ventral surface of a 

 portion of Segment 17 to show the papillae (pap.) connected by grooves with 

 the penis. The left papilla is on the boundary line between Segments 16 

 and 17 ; the right hand one in the latter segment, s. Setae. 



Fig. 20. — 17th and neighbouring segments of another individual. 



Fig. 21. — Heliodrilus. Ventral aspect of anterior segments to show 

 position of male pore ((^), spermathecal pore ( ? ), and papillae {pap.). 



Fig. 22. — Hyperiodrilus. A third individual, 17th and neighbouring 

 segments. In this specimen the papillae are symmetrical and upon the 17th 

 segment. 



Fig. 23. — Hyperiodrilus. Lateral view of genital segments, showing 

 oviducal pores ( $ ), nephridiopores («.), and male pore {$). 



Fig. 24. — Hyperiodrilus. Ventral view of 17th and neighbouring seg- 

 ments of same individual as that represented in Fig. 19. p. Penis, slightly 

 protruding from male pore. $ Spermathecal pore. pap. Papillae. 



Figs. 25 and 26. — Hyperiodrilus. Sections through ventral (Esophageal 

 pouch at two points ; for explanation see text. 



Fig. 27. — Hyperiodrilus. Vasa deferentia, with their peritoneal coat. 



Fig. 28. — Hyperiodrilus. Dilated portion of vas deferens. 



Fig. 29. — Heliodrilus. A portion of a section through the receptaculum 



