1920.] J. Stephenson: Oligochaeta from India and E. Persia. 199 



The dorsal setae begin in segment vi, and each bundle consists usually of one 

 hair and one needle seta; two hairs are sometimes found, in which case one is shorter 

 and thinner than the other ; once two hairs and two needles were seen, — the one 

 couple may perhaps have been destined to replace the other when they fell out. 



The hair is as a rule not quite equal in length to the diameter of the body. The 

 needles are about 45^ in length (hardly any can be measured accurately, owing to their 

 not lying flat), and bent at a very obtuse angle at a point rather distal to the middle 

 (fig. 3). The distal section of the seta is slightly curved in the contrary direction, — 

 very slightly only, so that the whole can hardly be described as sickle-shaped. There 

 is an indefinite nodulus at the angle in the shaft ; the length of the distal to that of 

 the proximal section of the shaft is about as 2 to 3. The tip is bifid, the two prongs 

 being visible to the ordinary high power of the microscope; the angle between the 

 two prongs is moderately wide, and the outer, which continues the direction of the 

 shaft, is slightly longer and perhaps slightly thinner than the inner. 



The ventral bundles, in all segments from vi onwards, consist of four or five setae,. 

 45 — 53M in length and 2 "5^ in thickness (fig. 4a). The nodulus is distal ; its exact 

 position on the shaft probably varies in the several setae of a bundle (cf. Stephenson, 

 10), though I was not able to obtain exact measurements. The prongs are equal in 

 length, the outer is not swollen at the base, and is only half or two-thirds as thick 

 as the inner. 



In the first four seta-bearing segments the form differs somewhat. The shafts 

 of the setae are thinner and straighter ; the nodulus is about the middle or a little proxi- 

 mal to the middle of the shaft; the outer prong is ij- times as long as the inner, two- 

 thirds as thick at the base, and more hooked (fig. 46). There are four setae per 

 bundle; their length is 50 to 56/", and their thickness only 2 •■ . 



Remarks: — The species to which the present comes nearest are N. tenuidentis 

 (Walton, 15) and N. raviensis (Stephenson, 9). The distinguishing character of the 

 former is the very long and slender prongs of the ventral setae, — hence- its specific 

 name. The separation of the present form from N. raviensis depends on the characters 

 of the setae, both dorsal and ventral ; the differences will be best realized by compar- 

 ing the figures given in the present paper with text-fig. 1 of my description of N. 

 raviensis. The most obvious are the position of the bend of the shaft of the dorsal 

 needles (much nearer the middle here), the relative lengths of anterior and posterior 

 ventral setae (the anterior are nearly twice as long as the posterior in N. raviensis), and 

 the characters of the prongs of the anterior ventral setae (in N. raviensis the outer is 

 very much the longer, and makes a very narrow angle with the inner). 



Genus Pristina. 

 Pristina longiseta, Ehrbg. 



Gwalior, Centra] India; in a pond, attached to Hydrilla and other débris. 18-vi-1917. 

 B. Prashad. One complete specimen, and perhaps one or two more in which the characteristic 

 proboscis or long setae were damaged. 



The toothing of thehair setae was only just visible with the oil immersion lens. 



