28 CALIFORNIA ACADEMY OF SCIENCES. 



once, in wliich it differs from the corresponding organ of' the two other species de- 

 scribed here. 



Septn/ f/lands (fig. 1). The septal glands of the cesophagus are found paired in 

 somites vi, vii, viii 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 scmie sjjecies of Ocnerodrilus, or as in Deltania Troyeri. 

 They are more nearly of tlie same size, and they extend all around the oesophagus 

 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 (fig!^. 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 0|)en, also, differently from other nephridia, their pores 

 being in front of and a little interim- (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 

 a])pear like large, ti-ansparent discs 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 \\\ the anterior pepto-nephridia, 

 gradually increasing in size backward, being largest in the post-clitellar ne^ihridia, 

 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 ne2)hridium in somite v 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-vesicles in the clitellum are about three to four times 

 shorter than the tubular part, while the ])ost-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 coecum, 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 



