STEUCTURE OP EARTHWORM ALLIED TO NEMERTODRILUS. 543 



also. The extent of the clitellum is more limited than in 

 other Eudrilids, where four to six segments appear to be the 

 rule. 



Sperm athecal Pore. — This is situated in the middle 

 ventral line (see fig. 2, sp) of Segment 13 ; it lies between 

 the ventral pairs of setae ; the aperture itself is small, but 

 its position is rendered somewhat conspicuous by being 

 placed upon the summit of a slight swelling of a yellowish 

 colour. 



Oviducal Pores. — These pores occupy what is, at present, 

 an unique position among earthworms. With the exception 

 of certain species of Moniligaster, and with the possible 

 exception of Eisenia (= Tetragonurus of Eisen), the ovi- 

 ducts of earthworms appear to open invariably upon the 14th 

 segment. In the present species they are situated on Seg- 

 ment 15. I took particular pains to assure myself that this 

 was really the case ; in half a dozen or so of individuals which 

 were marked by having these orifices very conspicuous they 

 were certainly situated on that segment. The oviducal pores 

 in this worm are not difficult to see ; indeed, these apertures 

 are for the most part particularly plain in the Eudrilidte. This 

 is due to the fact that the end of the oviduct is often slightly 

 protruded, and forms a round whitish elevation contrasting in 

 colour with the surrounding dark integument. I mention 

 these facts more particularly for the purpose of showing that 

 I am not likely to have fallen into an error in assigning this 

 abnormal position to the oviduct pore. The pore in Libyo- 

 drilus has the same appearance as I have figured and 

 described in Heliodrilus (1); that is to say, it is a whitish 

 knob upon the segment : it lies to the outside of and a 

 little in front of the" lateral pair of setse, but well behind the 

 groove which separates its segment (the 15th) from the 14th. 

 These are the only apertures belonging to the genital system 

 which are paired. 



The male genital pore is unpaired and median; it lies on 

 the border line of Segments 17, 18. The aperture lies upon 

 the summit of a conspicuous elevation of the integument; the 



