CALIFORNIA EUDRILIDA. 29 
general outline convex. ‘The anterior margin is convex-deltoid, with the apex at the 
exterior pore. 
The single duct from the vesicle leaves the vesicle in a different manner in 
the respective nephridia. In the pepto-nephridia it ascends from the center of the 
vesicle; in the anteclitellar vesicles it leaves from the apex of the deltoid longer part 
of the vesicle, while in the postclitellar nephridia it leaves from the side of the vesicle 
below the apex. The inner structure of the nephridia corresponds almost exactly 
with that of the nephridium of Argilophilus, which genus, however, does not possess a 
vesicle. With this exception, the nephridia of the two genera might be considered as 
almost identical. The most characteristic feature is that the short single duct from 
the nephridio-stome after joining the nephridial body, does not enter it as a single tube, 
but as a spongy duct full of irregular and connecting ductules, which later on join 
into one larger branching canal, the ductules, or arms of which enclose the two reg- 
ular underneath-lying ducts. At the inner bend of the duct the ductules disappear and 
the returning lobe contains three main canals, one of which is ciliated. This arrange- 
ment reminds us greatly of the one observed in certain leeches and described by 
Bourne. The vesicles consist of an outer muscular layer, which extends all around 
the bladder, and from it, along the duct through the clitellum or body-wall, to the 
exterior pore. Between it and the ccecal epithelium there is a continuous row of 
connecting chambers probably analogous with the ductules of the ducts. This epithe- 
lium is furnished with some few blood-vessels. The duct from the bladder to the 
nephridio-pore is not otherwise differentiated, the glandular cells of the clitellum joining 
directly on the muscular duct. Before reaching the pore but while in the body-wall, 
the duct is enlarged, forming a small pear-shaped urinary bladder, which again opens 
into a narrow duct surrounded by a row of long tubular cells, which open directly 
into the duct. These cells form a veritable collar, the upper cells lining the inner 
surface of the nephridio-pore (fig. 49). This in the elitellar nephridia. In the 
nephridia posterior to the clittellum, the long tube between the vesicle and the pore 
is entirely wanting, the bladder connecting directly with the collar of tubular cells 
(fig. 50). The tubules, or yacuols, in the vesicle collect into at least two tubes, which 
run downward between the muscular and glandular layers of the vesicle and appar- 
ently open on either side at the beginning of the collar at the nephridio-pore (figs. 49 
and 50). The secretion from this glandular layer of the bladder may be of such 
nature as to facilitate the ejection of coarse matter such as calculi which are found 
often in enormous quantities in the vesicle or seen as just ejected through the pores. 
The single duct which leads from the bladder to the nephridial body proper or the 
folded canals, apparently does not connect directly with the ductules or vacuols of 
the bladder, but opens directly into the large central chamber of the bladder, which 
again connects directly with the collar of the nephridio-pore. For a more detailed 
account of the canals of the nephridia in these two genera see the description of next 
genus, Argilophilus. Below the nephridial collar in De/tania elegans is found a large 
branching body, probably a ganglion. It sends out branches to the nephridial collar, 
though in my sections I haye not seen their actual connection with the collar. In 
