NEPHRIDIA OF THE AOTINOTROOHA IvARVA. 121 



Fig. 3. — Transverse isection t.liroii<xli llie front end of a newly-niefamor- 

 phosed larva, just in front of tlie anus. Tiie solenocytes have disappeared, 

 but the nephridial canals are seen to end blindly in the remains of the larval 

 prc-septal hseniocccl, now transformed into the adult ring-vessel of the lopho- 

 phore (ps. h.). Cam. Z. D, oc. 3. 



Fig, 4. — Sagittal section through the anterior end of a larva showing the 

 dorsal wall of the subneural pocket {d. w.) and the ventral diverticulum of 

 the stomach {d. v.). Cam. Z. D, oc. 2. 



Fig. 5. — Oblique longitudinal section of the nephridium passing through 

 its closed inner end, from which spring the solenocytes. Cam. ^^ oil immer- 

 sion, oc. 12. 



Fig. 6. — Section through the extreme tip of a nephridium lying in the 

 pre-septal lisemocoel. Below it runs tiie pre-scptal eoelomic canal. The 

 solenocytes are well shown. Cam. y'^ oil immersion, oc. 8. 



Fig. 7. — A few solenocytes drawn from a section to show the relation o 

 the nucleus to the tube. Cam. y^ oil immersion, oc. 8. 



Fig. 8. — Three solenocytes in transverse section. Cam. yV oil immersion, 

 oc. 8. 



Fig. 9. — Diagrammatic reconstruction of an Actinotrocha cut along a 

 frontal plane passing below the gut and nephridia behind, and cut more 

 dorsally in the upper half of the figurp. The subneural pocket is seen below 

 the brain. The oesophagus is cut transversely, two tentacles are cut longi- 

 tudinally, and the pre-septal coelom is cut across twice. 



Fig. 10. — Reconstruction of an oblique section parallel to and above the 

 septum, passing through the pre-septal ccelom. The anterior dorsal prolongation 

 of the trunk ccelom is cut into, the oesophagus and the ventral diverticulum are 

 cut across, and the blind ends of the nephridia are seen projecting into the 

 pre-septal hajmocoel. 



Fig. 11. — Frontal section passing through the ventral cajcum of the 

 stomach and in front of the ganglion. Cam. Z. A, oc. 3. 



Fig. 12. — Frontal section of tiie same series passing through the ganglion 

 and underlying subneural pocket. Cam. Z. A, oc. 2. 



Fig. 13. — Transverse section in front of the septum (compare fig. lU). 

 Cam. Z. D, oc. 3. 



Fig. 14. — Transverse section taken through the anterior region of the 

 trunk cavity and the posterior limits of tin; septum. The nephridia and tiie 

 ventral region of the pre-septal coelom are cut through. Cam. Z. D, oc. 3. 



Fig. 15. — Diagram of the nephridium of a young Actinotrociia showing the 

 canal and the solenocytes. 



