53 



rer, had not himself had an opportunity of examining the species, placed it, together 

 th C. gracilis Lilljeborg, in a separate group of Cyclopses (his gracilis-diaphanus 

 group). This arrangement cannot, however, be accepted. The 2 said species are 

 in reality very different, though apparently agreeing as to the number of joints 

 in the anterior antennae and the imperfect development of the last pair of legs. 

 I am inclined to refer C. gracilis, which, however, I unfortunately have not myself 

 had an opportunity of examining, to the succeeding genus, Mesocyclops, whereas 

 the present species is unquestionably a genuine Cyclops, and indeed so closely 

 allied to C. langvidus, that Dr. Schmeil was inclined to regard my C. nanus. which 

 as above stated is only a synonym of C. diaphanus, as merely a variety of C. 

 hutyriritis, the latter being referred by that author to his "bicuepidatits group". The 

 specific distinctness of the present form cannot, however, by rights be disputed, 

 as it differs from C. langvidus, not only in its much smaller size, but also in the 

 smaller number of joints in the anterior antennae, the imperfect development of 

 the last pair of legs, and finally in the shape of the caudal rami. 



Occurrence. I have only met with this form in a few places near Chri- 

 stiania, viz., in some shallow grassy pools lying close to the border of a large 

 lake, the Sognsvand. and apparently left by the reflux of the water in the 

 lake. A single specimen was also found last summer in Mj0sen, near Hamar, 

 at a depth of about 4 fathoms. 



Distribution. Sweden (Lilljeborg), Germany (Glaus), Russia (Fischer). 



30. Cyclops abyssieola, Lilljeborg. 



(PI. XXXII). 



Cyclops abyssieola, Lilljeborg, Svenska Arterna af SI. Cyclops. Kongl. 8v. Vet. Akad. Handl. 

 Bd. 35, No. 4, p. 66, PI. IV, figs. 1619. 



Specific Characters. Female. Body comparatively short and stout, with 

 the anterior division regularly oval in outline, greatest width considerably exceed- 

 ing half the length and occurring in the middle, frontal part narrowly rounded. 

 Lateral parts of the trunk-segments only slightly prominent and rounded off at 

 the end. Last trunk-segment very small and scarcely produced laterally. Genital 

 segment, on the other hand, of unusual size, exceeding in length the 3 succeeding 

 segments combined, and considerably dilated in front, being conspicuously broader 

 than the last trunk-segment. Caudal rami not much produced, being scarcely 

 longer than the last 2 segments combined, and not at all divergent ; seta of outer 

 edge not far from the apex and attached somewhat dorsally; middle apical 

 setae rather strong and somewhat unequal, the inner one being much the larger 



