274 OLIGOCHAETA 



are certainly capilliforrn, as in the majority of the genera, but they are really a little 

 different in form from the capilliform setae of other Tubificidae. The ventral setae are 

 quite different from those that occur in other genera ; there are two in each bundle, both 

 sigmoid but unnotched at the free extremity ; one of the two setae of each bundle 

 is decidedly larger than the other. The clitellum is more extensive than in other 

 Tubificids ; it appears to occupy some four segments, commencing with xii or xiii. 

 The alimentary tract is, with the exception of the buccal cavity, ciliated throughout ; 

 the intestine begins, though the transition is not very strongly marked, in segment xiii. 



The blood system is like that of Lophochacta and some other genera in that there 

 is a supra-intestinal vessel, which communicates with the ventral vessel by a single 

 paii' of ' intestinal hearts ' ; these latter are, however, apparently rather more than 

 merely connexions between the two longitudinal trunks ; their characters have been 

 already described elsewhere (p. 78). The testes lie in segments x, xi ; as one pair 

 are attached to the posterior wall of the former segment and the second pair to the 

 anterior wall of the latter, an appearance is presented of a single testis on each side 

 of the body perforating the septum ; this appears actually to be the case, the germinal 

 tissue being traceable through the septum ; the sperm-ducts are a single pair only ; 

 they open by their funnels into the eleventh segment ; the sperm-duct itself is entirely 

 enclosed in the following segment. The most remarkable fact about the sperm-duct is 

 the presence of a diverticulum, already referred to as arising from it, just within the sac 

 which surrounds the spermiducal gland ; the diverticulum is lined by an epithelium which 

 is not ciliated ; its structure, in fact, is precisely that of the spermathecae. The gland 

 is unusually long and very greatly coiled ; the terminal section appears to be protrusible 

 and passes straight from the external orifice upon the twelfth segment: the greater 

 part of the organ is contained within a sac which is formed by the splitting off of its 

 peritoneal coat ; this sac also contains the greater part of the windings of the sperm-duct, 

 and there are abundant bunches of spermatozoa lying loosely within its cavity ; the 

 sac, in all probability, performs the function of a sperm-sac, but how the spermatozoa 

 get into and out of it is a little difficult to understand, unless they actually pass 

 through the thin walls of the sac. The lining epithelium is not ciliated, and there is 

 no prostate. There are a pair of ovaries in segment xii, and the oviducts open 

 opposite to them. There are egg-sacs formed by a pushing back of the septum dividing 

 segments xii /xiii. 



The single pair of spermathecae lie in the fourteenth segment ; they are long 

 pouches dilated at the blind extremity, which in the fully mature worm is filled with 

 sperm ; the position of these organs behind the other parts of the reproductive system 

 is not found in any other Tubificid, but is known among the Lumbriculidae. The 



