35(5 ON CERTAIN POINTS IN THE ANATOMY OF THE POLYNOINA. 



Fig. 22. Diagram of the nephridium of the Polynoina : ci, ciliated internal opening ; /, lumen of tuhe ; 

 v, vesicle ; nepk, nephridial papilla ; cut, cuticle. 



Fig. 23. Polynoe spinifera, transverse section of nephridial papilla: cut, cuticle; ex. ep. epidermis; 

 ct, connective-tissue cells ; int. ep, epithelium of nephridial tube ; /. lumen of excretory duct. 

 x 550. 



Fig. 24. Polynoe spinifera, transverse section of nephridial tuhe near the internal opening : int. ep, ciliated 

 epithelium of wall of tube ; c, granular contents, x 550. 



Fig. 25. Polynoe spinifera, transverse section of excretory duct of nephridium in the region of the vesicle, 

 showing collapse of the walls owiug to the pressure of the ova in the coclom. 



Fig. 26. Polynoe spinifera, longitudinal section of a neuropodial cirrus, showing : — ct, branched connective- 

 tissue corpuscles ; c, large counective-tissue cells ; n, nerve, x 000. 



