igo8.] W. Michaelsen : Oligochceta of the Indian Empire and Ceylon. 209 



Remarks. — This variety is distinguished from the typical form of this species 

 principally by the smaller size and by the arrangement of the copulatory 

 organs, of which it possesses two, one on the 13th and one on the i8th segment, 

 whilst in the typical form there is only one on the 13th segment, backwards trans- 

 gressing somewhat the intersegmental furrow 13-14. There is probably also an 

 important difference in the shape of the spermathecae, but it is not quite 

 certain whether that described in the typical form should be regarded as completely 

 developed. 



OCTOCH^TUS PATTONI, M1CHI.SN. 



(Plate xiv, figs. 33—35) 

 O. p., MICHABLSEN, in Mt. Mus. Hamburg, xxiv, p. 170, f. 16. 

 Examined many partly mature specimens. 



External Characters. — Dimensions of mature specimens only slightly differ- 

 ing, lycngth about 90 mm., thickness in the middle about 3 mm., number of segments 

 about 180. 



Colour in general greyish, at the anterior segments dorsally brown. 



Head tanylobous (not always quite distinct, as the lateral furrow sometimes gets 

 indistinct behind) . Prostomium small, hardly broader than the hinder dorsal appendix. 



Setae moderately large, all at the ventral side of the body, the dorsal distance 

 being somewhat larger than half the circumference of the body {dd = --^.:u). Setae 

 paired, but not very strictly, the distance between the two setae of each pair measuring 

 about two- thirds of the median ventral and the median lateral distances {ab = cd = 

 I aa =f be). 



Clitellum mostly marked by a dark brown colour, ring-shaped or sometimes 

 interrupted ventrally in the median line, but without sharp borders along the inter- 

 ruption ; occupying segments 13 or | of 13 to 16 ( = 4 or 3^^). 



Prostate pores two pairs on the 17th and 19th segments in the lines of the setae 

 ab. 



Seminal furrows between the prostate pores of each side curving slightly 

 towards the median ventral line. 



Male pores in the seminal furrows on the i8th segment in the zone of setae 

 (not quite distinctly seen). 



The male area, bordered by the seminal furrows, very much deepened and sur- 

 rounded by thick swellings forming a biscuit-shaped wall which extends from the i6th 

 segment to the middle of the 20th segment. 



Female pores on the 14th segment closer together than the lines of setae a 

 and a Httle before the zone of setae, surrounded by a common, transverse, white biscuit- 

 shaped area. 



Sperma thecal pores two pairs in the intersegmental furrows 7-8 and 8-9, 

 all of them in the lines of setae a, or those of the hinder pair very little nearer 

 together. 



Copulatory organs: Large transversely oval glandular cushions with a de- 

 pression in the middle^ and a more or less distinct papilla on its centre, intersegmental. 



