448 TAGE SKOGSBERG 



of this genus th;it I investigated, developed as a very powerful moderately long, strongly cliitin- 

 ized digging claw, bent slightly upwards and directed somewhat forward, only slightly annulated; 

 it is denoted as the ,,a-claw" in the following descriptions of species. All the other bristles on 

 this joint are developed as sensory bristles.* The b-bristle is situated behind and somewhat 

 medially of the a-claw. It is of quite the same type in all the species investigated by me, about 

 as long as or rather slightly longer or shorter than the total length of the third to the seventh 

 joints; its proximal half is rather powerful and grows gradually narrower distally and is closely 

 annulated; its distal half is differentiated as a rather thin sensorial filament of about uniform 

 thickness and more or less completely hyaline; at about the middle of its anterior side there 

 issue, fairly close to each other, three subequal sensorial filaments, which are about half as long 

 as the bristle, and somewhat jjroximally of these there is a considerably shorter filament, which 

 is also situated on the anterior side of the bristle; the distal part of this bristle, like its filaments, 

 is partly furnished with extremely fine and short hairs. The c- and g-bristles: The c-bristle 

 is situated posteriorly and proximally on the joint, the g-bristle is somewhat in front of and distally 

 of the former. These are of the same type, subequal, about as long as the anterior side of the 

 second to the fourth or sometimes even the second to the sixth joints; they are rather powerful 

 proximally, closely annulated; they grow gradually narrower distally, the annulation dis- 

 appearing at the same time, and become a rather thin and more or less completely hyaline 

 sensorial filament; on the anterior side they have more or less uniformly distributed, moderately 

 long and rather thin sensorial filaments in moderate and somewhat varying number (from five 

 to nine were observed); these filaments are bare. The f-bristle is fixed laterally on the joint. 

 It is somewhat shorter than the c- and g-bristlcs and is of the same type as these. Its sensorial 

 filaments issue, however, on its posterior edge; this has probably some connection with the fact 

 tliat this bristle is always directed forward at about a right angle or even somewhat upwards, 

 while the b-, c- and g-bristles are only pointed very weakly forwaid. (Often, however, somewhat 

 more than is shown in the accompanying figures; for practical reasons one or more bristles have 

 been drawn in these figures pointing somewhat more ventrally than they actually did in the corre- 

 sponding preparations.) The number of sensorial filaments observed on this bristle was four 

 or five; the distal part of the bristle, like the filaments on the posterior side, are often partly 

 furnished with very fine, short hairs. The sensorial filaments on both b-, c-, f- and g-bristles 

 are of about equal thickness, more or less completely hyaline and. like the main bristle, distally 

 rounded and furnished at the point with a short, very fine hair. D- and e-bristles are situated 

 laterally, somewhat behind the f-bristle; they are simple, rather narrow and almost equally 

 thick sensorial filaments, rounded distally, closely and finely annulated, sometimes almost 

 hyaline distally. The e-bristle, often about as long as the total length of the third to the seventh 

 joints, is always well developed. The d-bristle is well developed in a number of species, but is 

 always somewhat weaker and shorter than the e-bristle; in most species, however, it is reduced; 

 even in these cases, however, I was always able to observe it on the species investigated by 



* G. W. MliLLKii (189'i) deiiolcs the d-brislle (like llu' seiisoi'y bristle (it tlie tiflh jniiil) by s. !>., sensory liristle, 

 which is, of course, iiol right, because, as has been pointed out above, all the bristles of the end joint, except the a-elaw, 

 are to be looked upon as sensory bristles (Cf. G, W. Mulleh, 189i, pis. 2, H and i). 



