THE NKPHRIDIA OF THE POLTCHJITA. 701 



the wall of the ncphridial canal, projecting into its lumen for 

 a certain distance (figs. 2, d, and 9). At their distal ends 

 they spring from rounded masses which look so like cells, 

 in the fresh, that I was at first deceived into the opinion that 

 they consisted of a row of large cells, each connected with 

 from four to six tubes (figs. 3 and 9). On further examina- 

 tion of stained preparations and sections, these rounded, long, 

 slightly granular masses proved to be made up of a large 

 number of small nuclei agglomerated together, and each be- 

 longing to its own tube (fig. 2). Cell outlines there are 

 none, and of cell substance scarcely a trace. A long flagel- 

 lum works rnpidly down each tube, passing into the lumen 

 of the nephridial canal. 



Characteristic of the nephridia of the Alciopinae is the 

 presence of long powerful cilia situated on the outer or 

 coelouiic surface of the organ in the regions where the 

 solenocytes are inserted. In Alciope, and perhaps to a less 

 extent in the other two genera, the tubes of the solenocytes 

 are regularly disposed in short transverse rows of from three 

 to six (fig. 4), and the outer cilia appear to work rapidly 

 backwards and forwards between these rows of tubes (figs. 

 3 and 9), thus renewing the coelomic fluid which bathes their 

 outer surfaces.^ 



Another detail worthy of notice is that in Asterope 

 Candida, and perhaps also in Alciope (figs. 9 and 2), the 

 bases of the tubes of the solenocytes are connected together 

 by a thin web for some distance. 



A large number of irregular vacuoles and globules, no 

 doubt of excretory nature, are generally found in the wall of 

 the nephi'idial canal (fig. 9). 



There is no internal opening whatever. 



The Genital Funnel. — In the quite anterior segments 



' Wlicn these nephridia are kept undisturbed for any length of time under 

 the cover-glass, the cilia soon cease to work ; but on the introduction of a 

 small drop of fresli sea water under the cover, both the outer cilia and the 

 flagella inside the tubes begin to work again with renewed vigour. The ces- 

 sation of movement is probably due to the want of oxygen. 



VOL. 43, PART 4. NEW SERIES. C C C 



