32 CRUSTACEA MALACOSTRACA. II. 



The main differences between this variety and the normal form are thus the slender spines 

 instead of processes on second and third joints of the antennae, the shape of the proximal half of 

 third antennular joint in the male, and the fact that the appendages of both head and thorax are on 

 the whole more robust. But I think it improbable that these differences are of specific value; adult 

 females with marsupium ought at least to be procured before the variety may possibly be separated 

 as a new species. 



Remarks. I established P. affinis on 3 females from the Kara Sea, while the insufficiency 

 of the literature on the genus and my very scanty material induced me to establish P. crassicornis 

 on a subadult male. I find it useful to insert here a more detailed description of female and sub- 

 adult male together with a number of figures, as I now possess a rich material both of this species 

 and of other forms. 



P. affinis is closely allied to P. macrocheles G. O. Sars, but if the figures published by Sars 

 (1897) are correct, the latter species differs especially in the outer ramus of the uropod, which is 

 shorter and showing a proportion between its joints quite different from the features found in P. af- 

 finis ; besides Sars has figured the antennulae with a strong seta, while a process is found in the typ- 

 ical specimens of P. affinis. Sars' figures of the legs differ also in minor particulars from P. affinis. 



Adult Male (PI. Ill, figs. 3 a 3b). A single adult male has been taken (at "Ingolf" St. 124) 

 together with two females. But though this specimen considerably resembles the male of P. forcipatiis, 

 I am not quite sure that it belongs to P. affinis. The head, seen from the side (fig. 3 a), has the an- 

 tero-lateral lobe still longer than in P. forcipatus, broadly rounded. The antennulse have the fifth 



joint slightly shorter than the sixth, which is scarcely as long as the seventh. The antennae thicker 

 than in the female; third joint proportionately long, as long as the penultimate joint, with a rather 

 long spine on the distal upper angle. The chelae shaped as in the male P. forcipatus, somewhat 

 more than twice as long as broad; the fixed finger at the base more than twice as broad as the 

 movable, which is somewhat shorter than the front margin of the hand; a narrow interval is seen 

 between the subdistal portions of the fingers. 



Second pair of legs (fig. 3 a) with the sixth joint a little shorter than the two preceding joints 

 combined, but as long as seventh joint with claw. Fourth pair of legs uncommonly short, only two- 

 thirds as long as the sixth pair; fifth pair, which are poorly preserved, seem also to be somewhat 

 short. The three posterior pairs have the sixth joint a little shorter than seventh joint with claw. 



The abdomen as to the shape of the lateral margins (fig. 3 b) and other particulars nearly as 

 in P. forcipatus, but sixth segment is proportionately longer and more produced backwards, reaching 

 slightly beyond the end of first joint of the endopod of the uropods, while the posterior margin is 

 somewhat broad and deeply emarginate as in P. forcipatus. The uropods differ much from those 



of the female; the endopod has the proximal joint much longer than the distal, the exopod reaches 

 slightly beyond the proximal joint of the endopod and its first joint is somewhat longer than 

 the second. 



Length of the single male 1.36""". 



The shape of the chelae and especially the relative length of the joints in the uropods as com- 

 pared with the corresponding organs of the female P. affinis make the reference of the adult male to 



