1917.] J- Stephenson : Indian Oligochaeta. 389 



the depressions on xvii, which they almost touch by their outer 

 ends ; the right aperture of the posterior pair has its centre in line 

 with that of the hinder sucker-like depression, and is situated 

 tangentially to it (fig. 12). 



The female aperture is situated midventrally on segment xiv, 

 in front of the line of the setae. 



The spermathecal apertures are two pairs, situated on segment 

 viii, the anterior in the line of the setae, the posterior just in front 

 of furrow 8/9. Each aperture appears as a small transverse slit 

 with slightly raised whitish lip ; the inner ends are not far from the 

 middle line. In none of the specimens could I make out any 

 actual pore within the transverse grooves ; and this was commonly 

 the case in other species of the genus also, so that the communi- 

 cation of the spermatheca with the exterior apparently takes place 

 only for a limited interval. 



A series of genital marks in the neighbourhood of the sperma- 

 thecal apertures is visible on close examination of this region. 

 These consist of a number of minute papillae, whitish, each with 

 a black central dot. These dots are displaced setae : on delicate 

 manipulation they can be felt to grate against a needle ; I isolated 

 some of them, and describe them below. The disposition of the 

 displaced setae in this particular specimen is shown in fig. 13 ; 

 briefly, there were three on segment vii, arranged more or less 

 transverseh" near the midventral line behind the middle of the 

 segment ; a transverse row of six on the anterior half of segment 

 viii ; and five on the anterior half of ix, three to the right and two to 

 the left of the middle line. An examination of the figure will show 

 that the displaced setae correspond in position to gaps in the 

 regular setal line, and further that the number in each group 

 corresponds to the number of setae missing from, the regular line ; 

 this is the case in the other species of the genus also. 



There is considerable variation in these external genital 

 characters. The sucker-like depressions may be more or less dis- 

 tinct ; the single posterior depression may be accurately in the 

 middle line ; or it may be rather further back than in the specimen 

 described above, over furrow iq/20 ; or finally the triangle may be 

 reversed, — there may be one anterior and two posterior depressions. 

 In the spermathecal region the anterior pair of spermathecal aper- 

 tures (or the grooves which are to contain them) may be just m 

 front of, rather than in the line of, tlie setae ; and displaced setae 

 may be absent on segment vii. 



Internal anatomy. — The disposition of the septa in the anterior 

 part of the body was not at first clear to me ; the difficulty arises 

 from the extreme tenuity of some of the septa, and the fact that 

 others are fused together in the manner to be described. Dissec- 

 tion of more than one specimen was necessary ; the result given 

 below was found to hold, in general terms, for the other species of 

 the genus also. 



Septum 4/5, behind the pharyngeal mass, is thin, but shows 

 the presence of a few muscular strands, and so is rather stronger 



