ON MONOPYLEPHORUS LIMOSUS. 39 



narrow duct passes from, behind the funnel through the eleventh 

 septum, rapidly changing into a thick tube for about half its course, 

 then narrows again and opens into a median chamber below the 

 nerve cord. This cavity, which may be called the median spermiducal 

 chamber, opens to the exterior towards the posterior end of the 

 eleventh segment by an irregular longitudinal aperture. The 

 openings of the sperm-ducts into the chamber are situated very 

 near together, close to the nerve cord " (Goodeich). " The structure 

 of the wide region (of the sperm-duct) .... its large size is chiefly 

 due to the covering of cœlomic epithelium cells, which have become 

 modified into long columnar cells with granular protoplasmic 

 contents " (Goodrich). " The oviducts appear to be reduced to a 

 mere depression on each side of the ventral edge of the twelfth 

 septum. The spermathecse are two pear-shaped sacs, opening in the 

 median ventral line by means of a common median pore immediately 

 below the nerve cord at the anterior end of the tenth segment. 

 It is interesting to note that in the young worm it shows that there 

 the two sperniathecee arise distinctly from right and left points 

 some distance from each other ; it is only later that the necks 

 of the two organs approximate and finally open by a common ap- 

 perture. .... Spermatophores have not been observed" (Good- 

 rich). 



It must be added that in this species the lateral horns of the 

 spermiducal chamber are well developed, as may be seen from 

 the following description of Ditlevsen : " Der Samenleiter besteht 

 aus einem Trichter im zehnten Segment und dem davon aus- 

 gehenden Samenleiter, der ganz kurz ist und aus drei Abschnitten 

 besteht, einem ungeheuer kurzen, dünnen, inwendig mit Wimper- 

 haaren bekleideten Rohre, einem mittleren, weiteren, auch mit 

 Wimperhaaren bekleideten Bohre, das äusserlich mit grossen 

 Peritonealzellen (?) bekleidet ist, und einem äusseren, mehr dick- 



