73 



lateral rib, which, as in the preceding species, is quite smooth. Posterior 

 antennne and anterior maxillipeds about as in that species. Posterior maxillipeds 

 with the last 2 joints well defined. Natatory legs comparatively more strongly 

 built than in the type species, with the rami broader; apical spines of inner 

 ramus in 4th pair rather strong, the inner one being the longer. Last pair of 

 legs somewhat more produced in relation to the width, and having the spine of 

 the inner edge still larger, with very coarse denticles on both edges. Ovisacs 

 comparatively large and considerably divergent. Seminal receptacle with the 

 anterior part evenly convex in front. 



Colour light olivaceous or yellowish grey. 



Length of adult female 1.20 to 1.50 mm. 



Remarks. This form, as stated above, was considered by Lilljeborg as 

 merely a variety of his species Cydops variiis (= C. agilis Koch). I think, how- 

 ever that it is entitled to be ranged as a distinct species, as it differs not 

 only in its much larger size, but also in some structural details mentioned in the 

 above diagnosis. 



Occurrence. I have hitherto only met with this form in 2 localities, viz., 

 in some small lagunes at the border of the lake 0stensj0, near Christiania, and 

 in widenings of the river Glommen. at Nipen. In both localities it only occurred 

 quite occasionally. 



Distribution. Sweden (Lilljeborg). 



43. Leptoeyclops Lilljeborgi, G. 0. Sars, new name. 



(PI. XLV). 

 Cyclops serrulatus, Lilljeborg, Synopsis, p. 81, PI. V, figs. 1 6 (not Fischer). 



Specific Characters. Femnl<'. Body somewhat less slender than in the 

 last-described species, and more resembling in shape that of L. agilis. Caudal 

 rami, however, more produced, nearly attaining the length of the last 3 segments 

 combined, and slightly flexuous, with the distal part somewhat divergent; outer 

 edge distinctly denticulated throughout, the denticles being especially conspicuous 

 in the distal part; middle apical setse of the usual structure; seta of inner corner 

 unusually prolonged, attaining almost the length of the corresponding ramus; 

 spine of outer corner likewise somewhat longer than usual, though much shorter 

 than the said seta. Anterior antennae long and slender, reaching, when reflexed, 

 to the end of the 2nd segment, lateral rib of the outer joints well marked and 

 on the proximal part of last joint divided into a number of well-marked denticles, 

 otherwise only very faintly striated. Posterior antennae and oral parts of normal 



10 Crustacea. 



