167 



gradually attenuated towards the end; palp tri-setose. Maxillipeds of normal 

 structure. Inner ramus of 4th pair of legs uniarticulate. Last pair of legs 

 quite rudimentary, each being replaced by a simple spine accompanied by 2 

 small bristles. 



Remarks.- This genus, established by Glaus, is chiefly characterised by 

 the rudimentary condition of the last pair of legs. Another character on which 

 still more stress has been laid by recent authors, is the reduction of the inner 

 ramus of the 4th pair of legs to a single joint. This character is, however, 

 not peculiar to the genus Pseudanthessius, but is also found in some species 

 of the genus Macwcheiron. Thus in the species mentioned above from the 

 Sargasso Sea, which in all other respects is closely allied to M. fnsicolnm, 

 the 2 joints of this ramus are wholly coalesced; and the same is also the case 

 with some of the Ceylon species described by A. Scott and, on account of 

 that character, erroneously referred to the genus Pseudanthessius, though from 

 the structure of the last pair of legs and other characters they must evidently 

 be included in the genus Macwcheiron, as here defined. 4 Norwegian species 

 referable to the present genus will be described below. 



89. Pseudanthessius gracilis, Glaus. 



(PI. XCIII). 

 Pseudanthessius gracilis, Glaus, Arbeiten d. xool. Inst. Wien, Vol. VIII, p. 344, PI. IV, figs. 1 7. 



Specific Characters. Female. Body rather slender, with the anterior 

 division moderately dilated and oblong oval in outline, greatest width in front 

 of the middle. Cephalic segment large, fully twice as long as the 3 succeeding 

 segments combined, and narrowly rounded in front. Last trunk-segment slightly 

 produced on each side. Tail very slender, somewhat exceeding half the length 

 of the anterior division; genital segment scarcely longer than the 3 succeeding 

 segments combined, and gradually widening posteriorly for about -'3 of its 

 length, then abruptly contracted, the hind third part being cylindric in form 

 and scarcely broader than the succeeding segment; anal segment nearly twice 

 as long as the preceding one. Caudal rami very slender and narrow, equalling 

 in length about half the remaining part of the tail, and scarcely at all diver- 

 gent; seta of outer edge attached near the middle; apical setae rather unequal 

 in length, the 2 middle ones being much longer than the other 2. Anterior 

 antennae comparatively slender and clothed with moderately long setae; 2nd 

 joint, as usual, the longest; terminal joint scarcely more than half as long as 

 the penultimate one. Posterior antennae moderately strong, with the 2nd joint 



