NOTES ON THE ANATOMY OP STERNASPIS. 245 



Fig. 12. — Exticmity of the stalk of a uepliridium, with its acconipauying 

 blood-vessels, and the ciliated funuel. From a stained preparation. X 400, 

 cam. 



Fig. 13. — Enlarged side view of a ciliated nephridial funnel, from the fresh. 



Fig. 14. — Enlarged view of the edge of a nephridial funnel, from the fresh. 



PLATE 16. 



Fig. 15. — Retracted Sternaspis, enlarged side view of a living specimen. 



Fig. 16, — Expanded Sternaspis; enlarged left side view from living and 

 preserved specimens. 



Fig. 17. — Enlarged inner view of the right half of a hardened expanded 

 specimen. The viscera have been removed, and the branchiae are not repre- 

 sented. 



Fig. 18. — Similar view of a retracted specimen. 



Fig. 19. — Enlarged inner view of the ventral portion of a retracted speci- 

 men, cut through horizontally. 



Fig. 20. — Similar view of the anterior end of an expanded specimen. 



Fig. 21. — Wall of the nephridium in optical section, showing the base of 

 the granule-bearing cells with their nuclei. From a stained preparation. 



Fig. 22. — Front and side view of nephridial granules, from a preparation 

 preserved in Hermann's fluid and stained with alum carmine. Cam. x 400. 



Fig. 23. — a. A portion of a nephridial cell teased out, showing the con- 

 tained granules. From the fresh, b. Isolated granules, more enlarged. 



Fig. 24. — Portion of the outer layer of the cuticle, with the foreign 

 particles fixed on to it. Cam. x 400. 



