structure. Natatory legs likewise much as in the preceding species, though having 

 the apical spines of the rarai more coarsely denticulate; those of inner ramus in 

 4th pair very unequal, the inner one being nearly twice as long as the outer. 

 Last pair of legs with the spine of the inner edge much feebler than in the 2 

 preceding species, and only minutely denticulated. Ovisacs of moderate size and 

 somewhat divergent. Seminal receptacle with the anterior part very broad, 

 occupying almost the whole width of the genital segment, and having the front 

 edge nearly straight. 



Colour olivaceous, with a more or less brownish tinge. 



Length of adult female only slightly exceeding 1 mm. 



Remarks. This form was identified by Lilljeborg with Cyclops serru- 

 /nlitx of Fischer, chiefly on account of a short note given by that author, according 

 to which, on a strong amplification, irregular rows of very small spinules were 

 traced on the outer joints of the anterior antennae. As however similar spinulos 

 are also stated to occur on the tail and on the trunk segments, it seems to me 

 very questionable whether this structure in reality refers to the dentate portion of 

 the lateral rib, as opined by Lilljeborg. In any case the figures given by Fischer 

 are evidently not referable to the present species but to C. ayilis Koch. Through 

 the kindness of Prof. Wiren of the Upsala University, I have had the opportunity 

 of examining the type specimens from which Lilljeborg's description was made. 



Occurrence. I have found this form occasionally in several places near 

 Christiania, sometimes in small tarns, sometimes in ponds and ditches. In a sample 

 taken in France by Dr. Sig. Thor, and kindly sent to me for examination, this 

 form occurred not unfrequently together with L. ayilis, and could at once be 

 distinguished from the latter by the rather different shape of the caudal rami. 



Distribution. Sweden (Lilljeborg), France (G. 0. Sars); very probably 

 also distributed in other parts of Europe. 



44. Leptocyclops maeruroides, (Lilljeborg). 



(PL XLVI). 

 < '//clops macruroideSj Lilli'eborg, Synopsis, p. 85, PI. V, figs. 7 11. 



Specific Characters. Female. Body somewhat more slender than in the 

 last described species, with the tail comparatively longer in proportion to the 

 anterior division. Caudal rami very narrow and prolonged, exceeding somewhat 

 in length the last 3 segments combined, and diverging very little, though some- 

 what remote at the base; outer edge distinctly denticulate throughout, seta of 

 that edge somewhat remote from the end ; middle apical seise of the usual 



