igi?-] J« Stephenson : Indian Oligochaeta. 279 



of the segment. In segment xii the vesicles may be described as a 

 pair, but fused in the middle line behind septum ii/r2, and thence 

 depending back on each side so as to bulge septum 12/13 back 

 nearly to the level of 13/14. All the vesicles are of simple outline 

 and not lobed. 



The prostates occupy segments xvii to xix, and are cut up into 

 three lobes, corresponding to the three segments ; they are how- 

 ever relatively small structures. The duct originates at the middle 

 of the gland, and passes at first backwards to the level of septum 

 18/19, then obliquely forwards and inwards ; the angle is perhaps 

 characteristic ; each duct is rather thin, soft, and broader towards 

 its ectal end. 



The spermathecae are situated in segments vii and viii, and 

 their ducts are directed forwards. The ampulla is sac-like and 

 irregular in shape ; the duct is half as thick and nearly as long as 

 the ampulla, from which it is not sharply marked off ; there is no 

 diverticulum. 



The penial setae, — those on each side of the male apertures, a 

 and b of segment xviii, — are but little modified. They are "4 mm. 

 in length, and 2Im broad at the middle ; there is a slight curve in 

 the proximal part of the shaft, and the tip is slightly bent ; the tip 

 is pointed, and near it there are a few fine dot-like sculpturings 

 arranged more or less in transverse rows (fig. 8). 



Remarks. — The present form belongs to the same group of 

 species as the last ; the characters of the male field and the penial 

 setae are probabl}^ sufficient to distinguish it, though its characters 

 are on the whole negative rather than positive. 



Perionyx aborensis, Stephenson var. heterochaetus, nov. 

 (PI. xvi, fig. 9). 



W. 138/1. Pashok, Darjiling Dist., E. Himalayas ; alt. 5000 ft. 26-v to 

 i4-vi-i9i6. F. H. Gravely. A single specimen. 



External characters. — 'Length 60 mm. ; breadth 2"5 mm. Colour 

 on dorsal surface dark purple anteriorly, brownish with darker 

 median stripe behind ; pale ventrally. The body is depressed, the 

 ventro lateral angles being fairly pronounced and the ventral sur- 

 face slightly concave. Segments 100. 



Prostomium epilobous J ; tongue broad, not closed behind. 



Dorsal pores from furrow 5/6. 



The setae, in rings, have a rather peculiar arrangement In 

 the fiist thirty-four segments the setae on the dorsal surface are 

 much larger, and set more widely apart, than behind; the change 

 is sudden, and coincides with a change in pigmentation, which is 

 darker and purpler in front, lighter and browner behind. In the 

 anterior part of the body zz is a little greater than y^,— about i^ yz ; 

 behind there is hardly any difference. The ventral setae are 

 comparatively small and close together throughout, and the ring 

 is closed {aa = ab). The following numbers were counted ; — 30/v, 



