48 



this rather common Cyclops, and no other species can properly be identified with 

 his C. pulehellus than the present one. The C. Thomasi of Forbes, which 

 both by Dr. Schmeil and Lilljeborg is recorded as only a synonym of the 

 present form, is in reality a well-defined species, as I have convinced myself by 

 an examination of specimens kindly sent to me by Prof. Forbes. The form at 

 first described by Prof. Brady as C. Lubbocki and subsequently as C. insignis 

 Glaus, seems to be referable to the variety odessana of the present species, and 

 this is also the case with C. helgolandicus of Rehberg. I have been in some doubt 

 as to whether the said variety should not more properly be regarded as a separate 

 species, as it differs from the typical form not only in the smaller number of 

 joints in the anterior antennae, but also in the comparatively shorter caudal rami, 

 and in a somewhat different shape of both the inner ramus of the 4th pair of 

 legs and of the last pair of legs, as shown in the accompanying plate. The 

 characteristic position of the seta on the outer edge of the caudal rami, as also 

 the mutual relation of the innermost and outermost apical setse, is, however, 

 exactly as in the typical form, and I have also found in some instances, that the 

 elongate 8th joint of the anterior antennae exhibits distinct traces of a subdivision 

 into the usual 4 short articulations. 



Occurrence. The present species is found not unfrequently in ponds and 

 ditches round Christiania, especially in the spring. I have also met with it 

 occasionally at the border of larger lakes, or in pools left by the reflux of the 

 water. In the living state it is easily recognised from the allied species by the 

 considerably diverging ovisacs, the ova of which often exhibit a light reddish 

 colour, as indicated in the figure given by Koch- The variety odessana I have 

 taken early in the spring from small water-holes with grassy bottom, the water 

 of which very soon evaporated. 



Distribution. Throughout the greater part of Europe, Central Asia 

 (G. 0. Sars), North America (Herrick). 



26. Cyclops bisetoSUS. Rehberg. 

 (PL XXVIII). 



Cyclops bisefosus, Rehberg, Beitrag zur Kentniss dor freilebenden Siisswasser-Copepoden. Abhandl. 



nat. Verein zu Bremen, Bd. VI, Heft 3, p. 543. 



Syn. : Cyclops bicuspidatus, Gr. O. Sars (not Clans). 







Specific Characters. Female. Body still more slender and attenuated 

 than in the preceding species. Lateral parts of penultimate trunk-segment not 

 extant. Last trunk-segment slightly produced laterally. Genital segment rather 



