•452 



Mr. TT. A. Baylis on a 



length ond 0'045 mm. in thickness. The portion distal to 

 the nodular thickening is much shorter than the proximal 

 portion, and only a very short piece projects beyond the 

 body-wall. 



The dorsal pores invariably begin at v./vi. The continuity 

 of the series is always broken by the absence of one or more 

 of the pores in front of the clitellum, as has been remarked 

 in the closely allied forms D. mourei and D.johnstoni *. The 

 pore at xi./xii. seems to be invariably absent, while of those 

 at x./xi. and at xii./xiii. one or both may also be missing. 



Fiir 1. 



Fig. 2. 



Fig. 1. — Dichogaster jaculatrix. Distal end of one of the penial setae, 

 Fly. 2. — llitto. Two ordinary chsetse. 



There is little doubt of the normal absence of these pores, as 

 the remainder are, in nearly all cases, well-expanded and 

 easily visible. The pore at xiii./xiv. is sometimes visible, but 

 the rest of the pores belonging to the segments of the 

 clitellum, if present, are greatly obscured, until near the 

 hinder end of the thickened epithelium. From xxi./xxii. or 

 xxii./xxiii. onwards there is a continuous series of pores. 



The apertures of the two pairs of spermatheca? occupy 

 their usual positions at vii./viii. and viii./ix., near the mid- 

 ventral line. 



* Beddard, Proc. Zool. Soc. 1901, ii. pp. 102, 199. 



