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SIDNEY F. HARMEK. 
through whose thick walls the examination of fine details is a 
matter of great difficulty. The proximal part consists of a 
small number of cells (fig. 17), which, in opposition to Joliet's 
statement, I consider undoubtedly excretory in function. The 
number of these cells seems to be invariably about four (L. 
crassicauda) ; they are of a distinct yellowish-green tint, the 
general appearance of which I have attempted to indicate in 
the figure, although on examination with high powers it is 
seen that this is entirely due to the presence of numerous 
granules which alone are coloured. The distal portion of the 
nephridium is a colourless duct, which presumably has no 
excretory function. In this portion only two nuclei were 
observed, the remainder of the duct being partly concealed by 
the oesophagus, although its cilia could be distinctly made out 
almost as far as the external opening (fig. 17). It seems to 
me certain that the two nephridia open independently, their 
apertures occurring in the depression of the vestibular floor 
situated behind the epistome ; there can be no doubt that 
the nephridia open to the exterior in front of the 
ganglion. The proximal portion is invariably curved, the 
concave side being internal, and the entire organ is perforated 
by a ciliated duct, beginning at its proximal end, and opening 
distally into the vestibule. The proximal cell I believe to be a 
flame-cell, as represented, although I am not prepared to state 
positively that this is really the case. In many individuals, 
however, I have felt satisfied that I have detected the single 
flagellum of the flame-cell, the difficulty consisting in the dis- 
tinction of the movement of a flagellum of this kind from the 
appearances produced by the co-ordinated movements of a 
series of cilia like those occurring in most parts of the nephri- 
dial duct. The proximal portion of the duct, which ends 
apparently csecally, is somewhat swollen, whilst the next 
portion is constricted ; at the bend of the nephridium, the duct 
increases very largely in calibre, the widened portion being 
continued slightly beyond the termination of the excretory 
cells, and thence narrowing to the aperture. The duct per- 
forates the individual cells of the nephridium, the cell limits 
