1920.] J. Stephenson: Oligochaeta from India and E. Persia. 233 



and attached to the ectal end, chambered and attached to the ectal end, and simple 



and attached (not merely attached but bound down by connective tissue) to near 



the middle of the sac. The variations are however so distributed that it is impossible 



to describe all the combinations as separate forms ; the one that I have named (var. 



riparius) is distinguishable on external examination by the marked difference in the 



male genital area. 



Octochaetus prashadi, sp. nov. 



Plate X, figs. 36-38. 



Kalyan, near Bombay. 7-vii-1917. B. Prashad. A single specimen. 



Sakarwari, on the way to Mahableshwar, W. Ghats. 4-vii-19l7. B. Prashad. Two speci- 

 mens. 



'External Characters: — Length 51-61 mm.; diameter 2*5-3'5 mm. Colour buff, 

 no pigmentation, no difference between dorsal and ventral surfaces. Segments ca. 

 150; v and vi biannular, some or all of the rest up to the clitellum triannular. 



Prostomium epilobous in varying degrees. 



Dorsal pores from furrow 12/13 (there may be a rudimentary pore in 11/12). 



There are some slight variations in the setal relations in the various specimens, 

 but they are not very different from the following : — In the anterior part of the body 

 ab = i t aa = foe = \ed, and the same behind the clitellum ; in the middle of the body 

 ab = \aa = half be = %cd. The dorsal interval dd = f of the circumference. 



The clitellum is absent, or very faint and indefinite. 



The male field shows a quadrangular thickening which includes part of xvi and 

 extends backwards to the hinder border of xx ; laterally it reaches to the line of setae 

 c. On segments xvii and xix are transverse trench-like depressions, deeper in their 

 lateral portions, where the prostatic pores are situated on rounded papillae in line 

 with setae b. The general aspect of the male area is thus not unlike that of the last 

 species. 



Here again is the same difficulty. One of the specimens from Sakarwari, though 

 corresponding closely in all other points, and especially in the peculiar penial and 

 copulatory setae, differs markedly from the other examples in the configuration of the 

 male field. The thickening is less extensive ; it does not get on to segment xx, and 

 laterally does not reach the line c ; there are no transverse depressions. Just possibly 

 the difference is due to the animal not being sexually as advanced as the others. 



The female pores are perhaps represented by a pair of small whitish dots near the 

 middle line on segment xiv, and nearly at the middle of the length of the segment. 



The ventral surfaces of segments viii and ix are thickened, especially, it may be, 

 round the sites of setae a and b ) these setae may not be visible, or they may be seen, 

 rather closer together than usual and shifted forwards nearer the anterior border of 

 the segment. The spermathecal apertures are in furrows 7/8 and 8/9, conspicuous, 

 in line with setae b, or between a and b. 



Internal Anatomy : — Septum 4/5 is somewhat thickened, 5/6 is thin, and 6/7 absent. 

 There is then some thickening as far as the clitellar region, most marked, perhaps, in 

 septa 9/10 and 10/11, and decreasing in front of and behind these. 



