ON A NEW ORGAN IN THE 'LYOORIDEA. 401 



Fig. 1. — Diagram of a transverse section, showing the posterior half of a 

 segment as seen from in front. For the sake of clearness the smaller blood- 

 vessels, setae, and all the muscles except the four main longitudinal muscles 

 have been omitted. The larger blood-vessels are shov?n on the left-hand side 

 of the figure. 



Fig. 2. — Diagrammatic side view of three segments from which the body, 

 wall and parapodia have been removed from the left side. Only the dorsal 

 and ventral blood-vessels are indicated. 



Fig. 3. — A branching ciliated process of the nephrostome. 

 Fig. 4. — Portion of sagittal section through two segments — above the 

 ventral edge of the dorsal muscle, below the dorsal edge of the ventral 

 muscle, between the two the coelomic cavity. The mass of fatty tissue which 

 fills the ccelom is not represented. The anterior segment is to the right. 

 Corrosive borax carm. Zeiss B., detail with high power. 



Fig. 5. — Upper part of a slightly oblique transverse section through the 

 middle of a segment. Corr. bor. car. Zeiss A., oc. 2, camera. 



Fig. 6. — Transverse section through the edge of the dorsal ciliated organ. 

 Corr. hsemat. Zeiss apochr. 4 mm., oc. 3, camera. 



Fig. 7. — Sagittal section cutting across the dorsal extension of the 

 coelom. The cuticle is not represented. Corr. bor. car. Zeiss D., oc. 3, 

 camera. 



Fig. 8. — Diagrammatic sketch of the nephridium and its canal, which is 

 subdivided into four regions. 



Fig. 9.— Optical section through the nephridial funnel, drawn from the 

 fresh, and completed from a stained specimen. Zeiss F., oc. 4. 



Fig. 9a. — Optical section through the nephridial funnel of Nereilepas 

 f ucata, Sav., drawn from the fresh, and completed after staining with alum 

 carmine. Zeiss apochr. 4 mm., oc. 4, camera. 



Fig. 10. — Portion of a transverse section, showing the nephridiopore. Corr. 

 bor. car. Zeiss apochr. 4 mm., oc. 8, camera. 



Fig. 11. — Transverse section through the third region of the nephridial 

 canal. Corr. hsemat. Zeiss 2 mm. oil im., oc. 8. 



Fig. 12. — Transverse section through the fourth region of the nephridial 

 canal. Corr. hsemat. Zeiss apochr. 4 mm., oc. 8. 



Fig. 12a. — Transverse section through the third region of the nephridial 

 canal. Hermann, haemat. Zeiss 2 mm. oil im., comp. oc. 4. 



Fig. 12^. — Section through the tissue between the coils of the nephridium, 

 showing network and connective-tissue cells. Hermann, hsemat. Zeiss 2 mm. 

 oil im., comp. oc. 4. 



Fig. 13. — Transverse section, slightly oblique, through the fourth region of 

 the nephridial canal. Corr. hsemat. Zeiss 2 mm. oil im., oc. 8. 



