82 



scarcely as long as the 3rd; the 4 outer joints very narrow and subequal in 

 size, constituting together the terminal part of the antenna, as shown by the 

 position of the aesthectask which is attached to the 3rd instead, as usual, to 

 the 4th joint. Posterior antennae with the outer ramus very minute and only 

 tipped with a single seta. Oral parts scarcely different from those in the other 

 species. Natatory legs with the inner ramus very small, uniarticulate; outer 

 ramus in the 3 posterior pairs exceedingly slender and narrow. Last pair of 

 legs with the proximal joint scarcely at all expanded inside, and only provided 

 with a single small seta on the posterior edge; distal joint narrow linear in 

 form, with a small bristle outside beyond the middle, and with 3 unequal 

 apical setae. 



Colour pale whitish grey. 



Length of adult female 0.84 mm. 



Remarks, The near relationship of the present form to the preceding 

 one is clearly shown by the presence of a quite similar spiniform process on 

 the dorsal face of the cephalic segment. It is however at once distinguished 

 from that species by the excessively prolonged and narrow caudal rami, as also 

 by the very small rostral projection. Some aberrant characters, as to the struc- 

 ture of the anterior antennae and legs, have moreover been indicated in the 

 above diagnosis. 



Occurrence. 2 or 3 female specimens only of this form have as yet 

 come under my notice. They were found at Ris0r at the considerable depth 

 of about 100 fathoms, muddy bottom. 



Distribution. Arctic Sea (Scott). 



67. Mesocletodes inermis, G. O. Sars, n. sp. 



(PI. LVI). 



Specific Characters. Female. Body resembling somewhat in shape 

 that of M. monensis, though on the whole rather more robust. Cephalic seg- 

 ment, as in that species, slightly contracted in front, with the rostral projection 

 well defined and rather prominent, tridentate; dorsal face of the segment not 

 much vaulted and without any trace of a spiniform process. Urosome about 

 the length of the anterior division, with the last segment rather large; anal 

 opercle not much prominent and edged with about 5 small denticles. Caudal 

 rami only slightly longer than the anal segment, but of the usual narrow linear 

 shape, with 2 small bristles, rather remote from each other, on the outer edge; 

 dorsal seta issuing somewhat beyond the middle; apical setae comparatively 



