236 
the ventral lip. Some of these vessels have blind dilated 
endings. The ventral lp is simple and slightly everted. 
x20: 
Fig. 29. ‘Two of the processes of the dorsal lip, from 
the second nephridium of a Laminarian specimen 190 mm. 
long, to show the multi-lobate edge. x 20. 
Fig. 30. Section of part of the excretory portion of 
the nephridium, from a young specimen 65 mm. long, 
showing two excretory cells with reticulate protoplasm 
and excretory granules in the distal portion. The 
granules become more numerous in older specimens, and 
are apparently extruded from the distal portion of the cell 
into the cavity of the nephridium. When this has recently 
occurred the distal part of the cell is very clear and free 
from granules. Hach cell bears one or two long flagella. 
Below the cells is a thin film of connective tissue (vepre- 
sented by a line) which is thicker in older specimens, and 
outside this the thin layer of coelomic epithelium, which 
covers the blood-vessels. x 650. 
Fig. 31.— The last nephridium of a living post-larval 
specimen 465 mm. long, in optical section. The larger 
(right in the figure) lip of the nephrostome bears seven 
protoplasmic processes (three are seen in the figure), 
hearing long cila directed towards the opening. The 
middle of the nephridium is slightly dilated and its walls 
contain excretory granules. The whole nephridium is 
ciliated. x 150. 
Fig. 52. The anterior end of the same nephridium 
drawn later. Optical section, showing the peculiar 
ciliated protoplasmic processes of the nephrostome, the 
cia of the nephridial tube, and the concretions in the 
walls of its middle position. x 600. 
Fig. 33. A process from the heart body of a speci- 
men 250 mm. long (see figs. 59 and 40), to show the 
