28 CALIFORNIA ACADEMY OF SCIENCES. 
once, in which it differs from the corresponding organ of the two other species de- 
scribed here. 
Septal glands (fig. 1). The septal glands of the esophagus are found paired in 
somites yi, vii, vill and ix. They are all comparatively small and very thin and 
flat. The posterior ones are smaller, but the difference between the glands is not 
so great as for instance in some species of Oenerodrilus, or as in Deltania Troyeri. 
They are more nearly of the same size, and they extend all around the cesophagus 
and are more or less divided in several separate lobes. We can, however, always 
distinguish one pair in each somite connected with the septum below the alimentary 
canal, extending upward with its free upper lobes, which do not connect. 
Nephridia (figs. 19 and 20). The nephridia commence in somite ii, and are 
found in all posterior somites. The three anterior nephridia—in ii, iii and iv—are 
slightly different as to size and outward form, and may be considered as a kind of 
pepto-nephridia. They open, also, differently from other nephridia, their pores 
being in front of and a little interior (nearer the ventral ganglion) to seta 4, while 
all other nephridia open in front of and interior to the third seta. The nephridio- 
pores of the clitellum are considerably larger than the pores in the other somites, and 
appear like large, transparent dises when viewed from the outside. All nephridia 
possess a vesicle or bladder next to the body-wall. A small collar of tubular cells 
surround the nephridio-pore. The vesicle is smaller in the anterior pepto-nephridia, 
gradually increasing in size backward, being largest in the post-clitellar nephridia, 
where it is several times larger than in the pepto-nephridia. In the three pairs of 
pepto-nephridia, the vesicles are almost circular, and of the same size in the three ne- 
phridia. That of the first common nephridium in somite y is of about the same size 
as the pepto-nephridial vesicles, but from this on the bladders increase gradually, but 
slowly, in size to the end of the clitellum. But in somite xviii and following to the 
end of the body, the vesicles are much larger, about twice as large as those in the 
clitellum. Thus the nephridio-yesicles in the clitellum are about three to four times 
shorter than the tubular part, while the post-clitellar vesicles are half, or more than 
half, as long as the tubular part or duct, when ordinarily folded. In the pepto- 
nephridia, the vesicle is about five times shorter than the folded tube, and the tubular 
duct extends more backward than in the other nephridia—especially so in the first 
nephridium 
encroaching on the next posterior somite, reaching diagonally across the 
somite, while all the other nephridia run parallel with the intersegmental grooves. 
This diagonal position of the nephridia is, however, not always constant, except in 
the most anterior nephridium. The vesicle in the posterior nephridia consists of two 
more or less distinct lobes, the posterior one (to the duct), which is more rounded 
and bladder-like, forming a ececum, and the anterior, which is elongated or deltoid. 
This difference is more pronounced in the posterior than in the anterior nephridia, 
most so in the nephridium in sonite xviii, which nephridium is generally the largest 
of all. From this somite the nephridia diminish somewhat in size, both anteriorly 
and posteriorly. The posterior margin of the vesicle is considerably lobed, and in 
