456 FRANK EK. BEDDARD. 
nephridial system and a complete circle of sete in each segment 
is the primitive condition be accepted, as greatly modified. 
We know, however, that within the limits of a single genus 
(Pericheta, Acanthodrilus), the nephridial system may 
become reduced to one pair of nephridia per somite, so that it 
is not necessary to assume that Eudrilus represents more 
nearly than any living form the ancestral Oligochet. I believe, 
however, that it does in respect of the reproductive organs.! 
The diffuse condition of the ovaries in many Planarians 
(which have already come to exhibit a regular segmental 
arrangement in Gunda), connected by a series of ducts with 
a single median pore” furnished with various accessory pouches, 
seems to me to be just recognisable in the female reproductive 
apparatus of Hudrilus. 
I would not, however, venture to assert that the continuity 
of ovary and oviduct is a direct inheritance from the Planarian. 
It seems to me to be rather a secondary modification comparable 
to the formation of the “ pericardium” in Deinodrilus, and 
to be the first step in the subdivision and partial obliteration of 
the coelom which culminates (as far as Annelids are concerned) 
in the Leeches, and in the Crustacea? and Mollusca. In 
saying this I do not mean to imply a belief in the old dis- 
tinction between ovaries independent of their duct and tubular 
ovaries, which has been urged with such ability by the brothers 
Hertwig in their “ Coelomtheorie.” 
1 Lang has figured (80, pl. 26, fig. 4) an ovary of Cycloporus 
papillosus which shows a remarkable resemblance to the ovary (of the 
fourteenth segment) in Hudrilus in being subdivided into a series of 
chambers. 
2 The two symmetrical pores of Hudrilus are not opposed to the above 
statement, for we know that in Pericheta there may be a single median 
pore, or two pores placed side by side, and there are other instances among 
Harthworms. 
3 See an abstract of a paper on the ccelom of Arthropods and Molluses by 
Professor Lankester in ‘Nature’ (1887), and Mr. Sedgwick “ On the Develop- 
_ment of Peripatus,” ‘Quart. Journ. Mier. Sci.,’ vol. xxvii. 
