1 66 DR. K. W. VERHOEFF ON BRACHYCHAETEUMA, 



with the close reticulation. The legs of the larvse have no 

 pointed tubercles. If, now, we disregard Dyocerasoma, the 

 larva of which have not been particularly investigated, the 

 larvae of Polymicrodon come nearest, among the five genera 

 named above, to those of Macheiriophoron. They may, 

 however, be distinguished by the following characters : — 



Macheiriophoron Larva. Polymicrodon Larvce. 



On the lateral keels there are The lateral keels are less arched 



raised longitudinal beads, hollowed and have no longitudinal beads 



out by a groove internally, and hollowed out internally, though ex- 



sharply marked off externally by a ternally there is a very deep longi- 



deep longitudinal furrow. These tudinal furrow. The lateral keels 



longitudinal beads bend posteriorly are anteriorly directed only slightly 



and internally obliquely towards the outwards. The tubercles of the 



hinder border of the segment. The posterior bristles are stronger, and 



lateral keels are somewhat obliquely when looked at from the side are 



bent outwards anteriorly. The clearly seen to project somewhat 



tubercles of the posterior bristles backwards. 

 do not project backwards. The 

 longitudinal beads are anteriorly 

 rounded, prominent and wide, pos- 

 teriorly strongly narrowed in the 

 form of fingers. 



The differences in the larvae partially correspond, therefore, 

 to those of the adults. The dorsal sculpture of the larvae is in 

 Polymicrodon coarser than that of the adults, whilst in the 

 shape of the hinder borders of the segments there is no 

 striking difference between larvae and adult males. This is in 

 contrast with the corresponding conditions in Macheiriophoron, 

 The larvae of Polymicrodon are easily separated from those 

 of Craspedosoma and Helvetiosoma by their sculpture; but 

 apart from this character the Polymicrodon larvae are still 

 further distinguished by their much smoother dorsal surface. 

 They are furthermore distinguished from the larvae of Craspe- 

 dosoma by the deeper longitudinal furrows on the lateral keels, 

 and from the larvae of Helvetiosoma by the absence of tubercles 

 on the coxa, prefemur and femur of the walking legs. 



