235 
so as to show the afferent branch to the nephridium. The 
afferent vessel of the fourth nephridium is accompanied 
by a solid cord of connective tissue. x 2. 
Priate IY. 
Fig. 24. Dissection of left side of fourth and fifth 
cheetigerous segments of a Laminarian specimen, showing 
second nephridium with blood-vessels, gonad, the muscles 
and the ventral! nerve cord. Three of the oblique muscles 
are interrupted to show the nephridium. x 4. 
Fig. 25. Second right nephridium of a young littoral 
specimen 44 min. long in dorsal aspect showing especially 
the capillary network on the funnel and excretory part, 
the processes on the dorsal iip, the position of the external 
opening (dotted), and the gonad upon the gonidial vessel. 
The edge of the ventral lip of the funnel is seen through 
the dorsal lip. x 69. 
Fig. 26. Fifth right nephridium of an adult male 
showing the vesicle distended with spermatozoa in dorsal 
aspect. The funnel of this nephridium was widely open, 
as is usual at the breeding season. x 4. 
Fig. 27. First left nephridium of a medium-sized 
worm, in dorsal aspect. This nephridium is much more 
slender than any of the others. The ventral lip of the 
funnel is shown (dotted) through the dorsal one. The 
gonidial vessel bears a number of blindly ending vascular 
processes which are covered with chlorogogen cells. x 8. 
Fig. 28. The anterior portion of the funnel of the 
fourth nephridium in ventral aspect. The dorsal lip bears 
numerous, almost semi-circular, lobed ciliated processes, 
each of which contains a blind diverticulum of the large 
blood-vessel which traverses this hp. On both lips there 
is a network of blood-vessels, but they are shown only on 
