486 ALFRED GIBBS BOCJENE. 



external apertures, and these correspond in position to the 

 most posteriorly placed pair of apertures in Pontobdella. Not 

 only here, but after much careful searching through several 

 complete series of sections of Branchellion, taken in various 

 planes, I have been unable to find any funnels ; indeed, I am 

 almost certain that none such exist. Branchellion would thus 

 present a more archaic form of nephridium than even Pon- 

 tobdella, and on this account is extremely interesting. 



Piscicola. 

 I have seen similar tubules in sections, and it is not difficult 

 to observe the external nephridial apertures in this genus ; ten 

 pairs may be counted. 



Clepsine. 



I have very little to add to Oscar Schultze's account 

 of the nephridia in this genus. I have found it perfectly 

 easy to trace the funnels in my sections : these open into 

 the ventral sinus (fig. 52). Following upon the neck of the 

 funnel is a dilatation corresponding to that described above in 

 Pontobdella, and as in the latter genus it becomes packed with 

 corpuscles. Following upon this (corresponding to the " testis 

 lobe *■' in Hirudo) is a single row of cells (woodcut, fig. 6, b.c.) 

 in which the lumen is only very feebly developed, the lumen 

 then enters the series of cells c—e, branching in the cells (see 

 woodcut, fig. 6, A b). The cut also shows how these cells are 

 penetrated in two places by the duct in its subsequent course. 



At e the lumen enters a series of very much elongated cells, 

 it passes onwards to what corresponds to the apical lobe in 

 Hirudo (</.) and then returns upon itself, perforating anotEer 

 series of elongated cells and returning to e, where with its own 

 special walls it passes through the series of rounded cells, e — c. 

 The section c. d. shows the two lumina each perforating its own 

 cell as they exist in the region e— /. At c the duct, perforating 

 another series of elongated cells as shown in the section e f, 

 passes down to the apical lobe and, perforating a single series 

 of cells, runs to /, across to e and once more with its own cell- 



