172 OLIGOCHAETA 



therefore, to that extent, different from, the female-ducts, graduate into them ; the 

 anterior pair of ducts in fact are longer than the second pair ; the latter, it is 

 true, are longer than the oviducts, but still they form a transition to them. The 

 absence of spermiducal glands here seems to me to be really a primitive character. 

 There are other facts, too, in the structure of the reproductive organs which argue 

 in favour of the primitive characters of the Phreoryctidae ; I have pointed out 

 elsewhere that in the embryo Lumbricus and Octochaetus there are four pairs of 

 gonads, of which only three come to maturity ; in certain species of Perichaeta 

 there are two pairs of egg-sacs, corresponding to the presumably ancestral two 

 pairs of ovaries ; now in Phreoryctes, at least in P. smithii, there are actually two 

 functional pairs of ovaries and oviducts. The development of Octochaetus seems 

 also to distinctly favour the view that the primitive form of generative duct is that 

 which only occupies two segments, the external pore being on the segment following 

 that which contains the funnel. In the development of that Annelid the ducts in 

 question ran straight to the body-wall, and there ended ; how the further growth 

 was effected I had no facts to enable me to judge. Besides, apart from the actual 

 facts of development, the necessity of assuming an early correspondence between 

 the male and female-ducts would lead to the assumption that the short male-ducts 

 were the most primitive ; there is no Oligochaet known in which the female-ducts 

 occupy more than one segment ; whereas there is every possible variation in the 

 number of segments occupied by the male-ducts; this of itself makes it probable 

 that the female-ducts represent the earlier condition. All arguments, therefore, appear 

 to me to point to the conclusion that Phreoryctes is, in respect of its reproductive 

 organs, the most primitive type. The vascular system of the Annelid is also in 

 a primitive condition, though not more so than that of the Tubificidae. The 

 development of Lumbricus (VEJDOVSKY) shows that a perivisceral trunk in each 

 segment of the body is the primitive condition ; apart altogether from the facts 

 of development, this would seem to be on a priori grounds likely; we know, too, 

 that the reduced number of the commissural vessels in the Naids is derived from 

 a more primitive condition, in which there was a perivisceral arch in each segment 

 (see below). In this respect Phreoryctes is primitive ; it is true that in one species 

 of the genus, at any rate, the periviscerals are not continuous round the body ; but 

 they are in P. smithii. 



There is no type in fact, in my opinion, which has such good claims to occupy 

 a low position among the Oligochaeta as Phreoryctes. It will be remembered also 

 that this genus is one which was placed by LANKESTER in a position intermediate 

 between the 'Limicolae' and the ' Terricolae ' of CLAPAKEDE; it does undoubtedly 



