164 DR. K. W. VERHOEFF ON BRACHYCHAETEUMA, 



The following notes may be given in regard to a few other 

 characters of Polymicrodon : Inner palpus of the gnathochi- 

 larium with four to five sensory processes on each side. 

 Promentum sharply marked off from the mentum by a furrow. 

 Grooved papillae broad, three-pointed. Third to eleventh 

 pairs of legs in the male provided with sucker-discs, which on 

 the eighth to eleventh occupy almost the whole of the distal 

 half, but leave the thin portion of the distal claw free. The 

 coxal sacs of the eighth and ninth pairs of legs are strikingly 

 small and contain a fine-grained sperm. There are no other 

 special characters in the third to the eleventh pairs of legs. 

 The inferior margin of the seventh pleurotergite of the male is 

 somewhat hollowed out in two places, more strongly in front 

 than behind, and standing out in a rounded projection 

 between the two excavations. 



The form and structure of the abdominal segments in the 

 genera of Craspedosomidse with which we are here concerned 

 I have already discussed on pages 24 and 25 of my 37th 

 paper; I have there emphasised the fact that it is Macheirio- 

 phoron which is especially distinguished from its relatives in 

 these respects. In Polymicrodon the lateral keels of the 

 abdominal segments are broad, and posteriorly have an 

 almost straight margin. They are further distinguished by 

 specially deep marginal grooves, which are best seen when 

 the specimen is held transversely to the direction of the light. 

 From the side the marginal groove is seen to run from the 

 anterior to the posterior bristle ; the latter is placed on a 

 little papilla which plainly projects over the posterior border 

 towards the rear. (In Macheiriophoron not only is the 

 marginal groove weaker, but from the side the papilla of the 

 posterior bristle is not seen to project, because the lateral 

 keels are so strongly bent outwards obliquely towards the 

 front.) The posterior edge of the pleurotergites in Polymi- 

 crodon runs almost straight in the middle, and forms on each 

 side an obtuse angle with the almost straight hinder edge of 

 the lateral keel, whilst in Macheiriophoron the posterior edge 

 runs in curves, a rounded flap projecting on each side, and 



