47 

 25. Cyclops pulchellus, Koch. 



(PI. XXVII). 



Cyclops pulchellus, Koch, 1. c. Heft 21, 2. 

 Syn. : Cyclops bicuspidatus, Glaus. 

 Lubbocki, Brady. 



insignis, Brady (not Claus). 



odessanus, Schmankewitsch. 



helgolandicus, Rehberg. 



Specific Characters. Female. Body rather slender and attenuated, with 

 the anterior divison oblong oval in outline, greatest width about equalling half 

 the length and occurring in the middle. Lateral parts of penultimate trunk- 

 segment not extant, resembling in shape those of the 2 preceding segments. 

 Last trunk-segment only slightly produced laterally. Genital segment comparatively 

 large and gradually narrowed behind. Caudal rami long and slender, generally 

 attaining the length of the last 3 segments combined, and not at all divergent; 

 seta of outer edge at a considerable distance from the apex, being attached 

 not far from the middle of the corresponding ramus ; middle apical seta3 rather 

 slender, the inner one being much the longer and about equalling the tail in 

 length; seta of inner corner very little longer than that of the outer, and much 

 thinner. Anterior antennae about the length of the cephalic segment and gener- 

 ally 17-articulate; in some instances, however, by the concrescence of the 8th to 

 llth joints, only 14-articulate. Posterior antenna? with the terminal joint slightly 

 longer and narrower than the penultimate one. Natatory legs comparatively 

 slender, with only 2 spines outside the terminal joint of the outer raraus; apical 

 spines of inner ramus in 4th pair rather unequal, the outer one being much the 

 larger. Last pair of legs with the proximal joint comparatively small, distal 

 joint more than twice as long, and narrow linear in form, lateral spine rather 

 slender and attached at a short distance from the end. Ovisacs generally narrow 

 oblong or fusiform in shape, and considerably diverging. Seminal receptacle with 

 the posterior part rather produced. 



Colour generally yellowish, with a more or less distinct orange or reddish 

 tinge, in some instances, however, uniformly whitish grey. 



Length of adult female amounting to 1.30 mm. 



Remarks. My original identification of this form with C. pulchellus of 

 Koch has not been admitted by Dr. Schmeil, and the present species has there- 

 fore by most recent authors, and also by myself, been recorded under the name 

 bicuspidatus given to it by Claus. I now find, however, that there are so many 

 things which speak in favour of my former identification, that I have thought it 

 right to maintain it here. It must indeed be assumed that Koch has observed 



