OLIGOCHAETA. 



{Supplementary Report). 



By J. Stephenson. 



A number of small worms, which proved to be of the above species, were kindly 

 sent to me for examination a short time ago by Dr. Annandale. The species has 

 hitherto been recorded, so far as I have been able to discover, by only two observ- 

 ers, — Ditlevsen, who found it in Denmark, and Moore, in the United States. The 

 genus to which it belongs, however, has also been found in England, Japan, the 

 Kermadec and Auckland Islands, and the Transvaal (I include the identical or closely 

 allied Rhizodrilus), and thus is cosmopolitan. From a zoogeographical point of view 

 therefore the present record is not of much importance. The worm is however inter- 

 esting, inasmuch as the fusion of the originally paired genital apertures in the middle 

 line has here been followed by the disappearance of the spermatheca of the right 

 side. 



Monopylephorus parvus, Ditlevsen. 



Barkuda I., Chilka Lake, Ganjam Dist., Madras Pres. ; among rotting water-weeds at edge of 

 lake (Annandale and- Gravely); 15 — 22-VÜ-1916. Numerous specimens. 



Two short accounts of the anatomy of this worm have already been given (Ditlev- 

 sen, 3 ; Moore, 6). The following description is fairly complete, and adds a number 

 of particulars, more especially with regard to the setae and genital apparatus. 



The maximum length of the specimens was half an inch, or about 12 mm., and 

 their thickness about -35 mm. They were whitish or grey in colour (pink during life). 

 The external segmentation was very well marked, the segments being divided by very 

 distinct constrictions, and bulging out between these. The number of segments 

 counted in a good-sized specimen was 64 ; there were no secondary annulations. 



The prostomium is large, prominent, and triangular in shape with rounded tip. 



The clitellum embraces about the posterior two-fifths of segment x, and the 

 whole of xi and xii. 



The setae are of two forms, single-pointed and double-pointed curved needles 

 (crotchets) ; both kinds occur in both dorsal and ventral bundles. There are no hair- 

 setae. 



The double-pointed needles (fig. la) are 8o/x in length, — those of the anterior 

 bundles perhaps a trifle longer; in thickness they are about 3m. The nodulus is 

 somewhat distal to the middle of the shaft. The prongs are equal in length, or the 

 outer may sometimes seem to be slightly the longer, and both are comparatively 

 short; anteriorly, the rule is that the prongs are nearly equal in thickness, but the 



