SOME POINTS IN THE ANATOMY OF POLYCHJITA. 277 



Fig. 4. — Horizontal section through three somites, from middle part of 

 body of the same species, ne., se., as before. An ovum is seen in one of the 

 neplirostomata. A, Zeiss, oc. 2. 



Fig. 5. — Transverse section of same species, middle part of body, passing 

 through external openings of a pair of nephridia. A, Zeiss, oc. 2. 



Fig. 6.— Two somites of Cirratulus cirrafus, seen living bv reflected 

 light while the eggs were escaping. In one somite an ovum is shown just 

 emerging from the nephridial aperture. 



Fig. 7. — Portions of two consecutive somites, from a vertical longitudinal 

 section of Nerine cirratulus. ne. Nephrostomy ov. Ovary, tw. Notopo- 

 dial chaetje. nu. Neuropodial chaetse. 



Fig. 8. — Portion of a section of the same series as the preceding, nearer 

 the surface of the body, no., nu., as before. np. External opening of the 

 nephridium. 



Fig. 9. — Longitudinal vertical section of Nerine coniocephala, showing 

 relations of the nephridium. Reference letters as before. 



Fig. 10. — Fresh preparation made by cutting open the anterior part of a 

 specimen of Lanice conchilega along the dorsal median line, taking away 

 the intestine and cutting through the oblique muscles on each side. n. Ne- 

 phridia, with looped tubes. n'. Reduced nephridia. n. r. Rudimentary 

 nephridium of 5th somite, no. Notopodial chajtaj, their inner ends. 



Fig. 11. — Horizontal section of anterior nine somites of Lanice conchi- 

 lega, at a level near upper end of the uncinigerous tori. n. Continuous 

 tube formed by nephridia of Somites vi to ix. n. a. Ascending part of 

 nephridial tube. n. p. Nephridial aperture, v. gl. Tissue of ventral glandu- 

 lar epidermis. 



Fig. 12. — Similar horizontal section of Somites xi to xiv. n'. Coalesced 

 reduced nephridia. nu. Neuropodium, i. e. uncinigerous torus. 



Fig. 13. — Horizontal section of somites n to v of Lanice conchilega, 

 from the same series as that shown in Fig. 11. ne., ne., ne. Neplirostomata 

 of Somites n, in, and iv, with gonads attached to the posterior two. n. 

 Section of nephridial tube in Somite m. 



Fig. 14. — Transverse section of Lanice conchilega in Somite x. «'• 

 Cavity of reduced nephridium. d. b. Dorsal blood-vessel. v. gl. Ventral 

 glandular epidermis. 



Fig. 15. — Nephridium of Nereis virens, as seen in fresh state, when 

 dissected out from the animal, ne. Nephrostorne with its fringe of branched 

 ciliated proces-ses. n. Globular mass, formed by the convoluted nephridial 

 tube. n. p. Cylindrical portion leading to external aperture. A, Zeiss, oc. 2. 



Fig. 16. — Nephrostorne of Nereis virens, more highly magnified; fresh 

 condition. Zeiss, C C, oc. 3. 



