224 



PROF. W. B. BENHAM ON AQUATIC 



[Nov. 3, 



of the ventral chasta. A transverse section through the sperm- 

 duct has all the appearance of a section across a nephridium : we 

 see, not an epithelium surrounding the lumen, but a perforated 

 cell with rarely more than one nucleus in the plane of the section, 



Text-fig. 23. 



Plan of genital organs in Saplotaxis Tieterogyne, composed from study of entire 

 worm and sections. The gonads are omitted on the right side in order to 

 show the full course of the sperm-ducts, each of which leaves its funnel at its 

 ventral edge ; it has a course similar to that of a nephridium, and, like the 

 latter, traverses a cord of cells. 



Ne}, the first nephridium; Ne.^, the second; Ne.f., nephridial funnel; O.d., 

 oviduct ; O.s., ovisac ; Ov., ovary ; Sp.d., sperm-duct ; Sp.f., sperm-funnel ; Sp.s., 

 sperm-sac; /SpiA., spermatheca; f., testis. 



