636 MR FRANK E. BEDDARD ON THE 



Affinities of Phreoryctes. 



Before discussing the affinities of Phreoryctes to other Oligochseta, it is necessary to 

 inquire the relations of the present species to Phreoryctes Menkeanus and Phreoryctes 

 filiformis ; this it is a little difficult to do satisfactorily, inasmuch as our knowledge of 

 the reproductive organs of these two species is very meagre ; and generic and family 

 distinctions are chiefly based upon variations of the reproductive system. With regard 

 to Phreoryctes jiliformis, Vejdovsky [A 11] is unable to make any statements whatever 

 about the reproductive organs ; he did not discover a trace of these organs in that 

 species. Of Phreoryctes Menkeanus we know something about the gonads and the 

 spermathecse ; the only investigators who have discovered these organs in Phreoryctes 

 Menkeanus are Leydig [A 7] and Timm [A 10] ; according to Timm, there are three 

 pairs of spermathecae situated respectively in segments VI., VII., and VIII.; these organs 

 seem to be distinguished by their extraordinarily thick muscular walls. Both observers 

 agree that there are four pairs of gonads, considered to be testes, situated in segments IX., 

 X., XL, XII. Vejdovsky [A 11] has remarked that in all probability these supposed 

 testes are in reality both testes and ovaries. Both Leydig and Timm failed to find any 

 generative ducts ; and Timm supports the view of Leydig that the nephridia of the 

 genital segments serve as efferent ducts. Although these descriptions are incomplete, 

 they are, I think, sufficient to point to the conclusion that my species is a congener of 

 Phreoryctes Menkeanus. It is so very rare among the Oligochseta for there to be four 

 pairs of gonads (two pairs of testes and two pairs of ovaries), that this fact of agreement 

 alone appears to demonstrate the generic identity of the two forms. 



The difference in position of the gonads, commencing as they are stated to do in the 

 IXth segment in Phreoryctes Menkeanus and in the Xth segment in Phreoryctes 

 Smithii, is due to a difference* in the way of enumerating the segments of the former 

 species. 



The reason why neither Leydig nor Timm succeeded in discovering the reproductive 

 ducts, may have been the extreme difficulty of seeing these structures in immature 

 specimens. I have already pointed out that the funnels are made up of only one layer 

 of cells closely pressed against the septum, and as the duct opens close to the posterior 

 side of the same septum, there is no great length of vas deferens to attract the eye in 

 transverse or longitudinal sections. It is perhaps more probable that in the specimens 

 studied by Leydig and Timm they were even more rudimentary than in the specimen 

 originally described by myself. That this was the case is rendered likely by the 

 occurrence of nephridia in these segments, which, as we know from the discoveries of 

 Vejdovsky, are present, in aquatic Oligochseta, in the genital segments before the 

 generative ducts make their appearance ; when the vasa deferentia and oviducts are 

 developed the nephridia of their segments atrophy and eventually disappear. 



* In this paper I count the peristomial segment as the first segment. 



