388 



ARKIV FÖR ZOOLOGI. BAXD 1. 



distal part of the low ridges which, one on each side, run 

 backwards and outwards from the beginning of the said 

 furrow, there is a row of small tubercles which, in the case 

 of some individuals, are each armed with a small spine. 



The hinder edge of the lamellse and the telson are fur- 

 nished with a row of plnme-shaped hairs, which seem to be 

 jointed; or it may be that tkey are only marked with transverse 

 streaks. Hairs of the same shape, but with shorter joints or 

 shorter distances between the transverse streaks, are also to 

 be found on the swimmerets (Pl. 21, fig. 6). Intermixed with 

 some comparatively very long hairs there is, at the said edge 

 of the telson and the lamellse, a second row of hairs, these 

 being very short, like small spines. The latter row does not 

 reach to the corners of the lanielhe or of the telson. 



As will be seen from the following tabnlar scheme, which 

 has been compiled by Mr. G. Lilljevall, the drawer of the 

 plates, the telson seems to be narrower in the male than in 

 the female: 



It seems to be likely too, that a larger individual of the 

 same sex has a comparatively narrower telson than a smaller 

 (youDger) one. 



The flrst abdominal segment is, in the case of the egg- 

 bearing and the medinm-sized femaJe, provided with a pair 

 of one-jointed, rudimentary feet (Pl. 21, fig. 4 a) which 

 are not found in the other specimens. 



The two branches of the second pair of abdominal limbs 

 seem to be mnlti-articulated (P.l 21. fig. 5, (> and 7), but I 

 am not quite sure if these are real joints or a wall running. 

 perhaps, in a spiral-form (ef. fig. 6). The hairs are plume- 

 shaped and seemingly articulated (fig. 6). Where the inner 

 branch becomes abruptly narrower, we find, in the case of 



