224. FRANK K. BEDDARD. 
ened, but not so greatly as is so often the case. The next 
septum is also thicker than those which follow, but not so 
thick as those which precede it. All these thickened septa lie 
behind the gizzard. The anterior septa are cup-shaped. 
The alimentary canal is differentiated into a gizzard 
which lies in the 6th segment. It is long and rather narrow. 
The cesophagus which follows extends as far as the 17th seg- 
ment. It is very vascular throughout its whole length, and 
the lining membrane is so folded that in cross sections the 
edges look like a mass of tubes containing blood and cut 
across. The cesophagus is entirely unprovided with glands of 
any kind appended to it. The intestine has a very small 
typhlosole. 
The nephridia are paired structures. Those of the pos- 
terior segments are, as is the general rule, much more obvious 
in dissections than the few most anterior. This is due to the 
development of the peritoneal cells which clothe them. These 
cells are often filled with quite large lumps of an amorphous 
secretion which stains darkly in borax carmine. It is these 
secretions which give the white colour and therefore the con- 
spicuous appearance to the nephridia in the posterior segments. 
When the worm was examined with a hand lens, or even 
mounted in glycerine on a slide and studied with compara- 
tively high powers of the microscope, there was no indication 
of nephridiopores. These are usually conspicuous in the 
Eudrilide, but they were absolutely invisible in Pareu- 
drilus. 
The reason for the apparent absence of nephridiopores was 
revealed by an examination of transverse sections. In such 
preparations the duct of the nephridium could be easily traced 
into the body-wall in the region of the ventral pair of sete ; the 
duct of the nephridium was quite obvious on account of its 
considerable width, and the fact that it has an intercellular 
lumen. Directly it penetrates the body-wall it becomes of less 
calibre, and instead of opening on to the exterior forms a duct 
which runs right round the body-wall on the boundary line 
between the two muscular layers, and in immediate proximity 
