Stmlics on Tii.'ir'im' Oslriirmls 893 



sensorial tilanieuts; in tlie specimens iiom ucjitliern l<jcalities, Spitzbergen, (Greenland, etc. 

 one of these distal sensorial filaments was somewhat displaced proximally. The d-, e- and 

 g-bristles are subequal, about as long as the total length of the three distal joints. The last- 

 mentioned one has three proximal and four distal sensorial filaments, thus the same number 

 as in the female. The c- and f-bristles are subequal or else the latter is somewhat shorter than 

 the former; on all the specimens investigated the c-bristie had thirteen, the f-bristle twelve 

 sensorial filaments, distributed fairly uniformly along the whole length of the bristle. The 

 hairs on this limb are somewhat more weakly developed than in the female. 



Second antenna: — E x o p o d i t e (fig. 10) : This has about the following 

 proportions between its joints: 



I : II : III : IV : V : VI : VII : VIII : IX = 15 : 6 : 9 : 2 : 2 : 2 : 1.5 : J : 0,5, 



i. e. the first joint is about as long as the total length of the second and tliird joints and the 

 third joint is about as long as the total length of all the following joints. The bristle on the 

 second joint is furnished ventrally at about the middle or somewhat proximally to this point 

 with about four to six rather strong, smooth spines. The natatory hairs on tlie natatory bristles 

 are perhaps somewhat wider than in the female. The end joint has only six bristles, one of the 

 shorter ones of the female being missing; either both the two short bristles on this joint are 

 provided with long natatory hairs or else the shorter one of them has short hairs. E n d o- 

 p o d i t e (fig. 11): The first joint has quite the same equipment of bristles as in the female. 

 The second and the third joints are long and of about the same length. The former has ventrally 

 at the middle three moderately long, subequal bristles with short hairs. The latter is rather 

 strongly bent; its concave side, which is turned towards the second joint, is somewhat undulated 

 and has about five or six weak transverse chitinous ridges distally and no deep notch proximallv; 

 its proximal bristle is rather short, about a quarter or a third of the length of the joint, and 

 rounded distally; its two distal bristles are subequal, about as long as the distal breadth 

 of the joint. 



Mandible: — P r o t o p o d i t e: The endite of the coxale is sometimes of about 

 the type shown in the figure 13, sometimes it is of about the same type as in the tVmale, 

 only considerably smaller. The two Tnain points are sometimes of about equal length, sometimes 

 one is rather considerably longer t-han the other; the latter seems to be most often the case; 

 the chitinization is weak, the bristle situated laterally at the base is similar to that in the female; 

 there is most often scarcely any armature. Basale: The six proximal-medial bristles are of 

 about the same length as in the female, all rather weak and finely pectinated; most of them are 

 without any long secondary bristles; only the distal one often has a wreath of them at the 

 middle. This joint has six or seven bristles ventrally, of the same length as in the female; the 

 proximal ones have considerably more abundant long secondary bristles; these secondary bristles 

 are, however, less stiff. Of the four dorsal bristles on this joint the long distal bristle is about 

 the same as in the female, the three others are in most cases relatively shorter and liave no 

 long secondary bristles. The two bristles of the e x o j:* o d i t e are in most cases without auv 

 long secondary bristles; sometimes, however, one or even both may have a wreath of these bristles 



Zoolog. bidrag, Upi)sala. Suppl.-Bd. I. 50 



