45 



scarcely produced at all behind. Spermatophores attached to the genital opening 

 small and placed longitudinally close together. 



Colour light yellowish, with a more or less distinct reddish or ochra- 

 ceous tinge. 



Length of adult female 1.40 1.50 mm. 



Remarks. I have thought it right to maintain my original identification 

 of this form with C. lucidulus of Koch, in spite of the controversy of Dr. Schmeil. 

 It is true, that the description given by Koch of this species, as pointed out by 

 Dr. Schmeil, is quite insufficient, but nevertheless I find it possible to recognise the 

 species from the figure accompanying the description, and Dr. Eehberg is also of 

 opinion that my identification is correct. The species has generally been recorded 

 under the name vernalis proposed for it by Fischer; but this name is of much later 

 date than that given to the species by Koch. The Cyclops elongatus of Glaus 

 is certainly the same species, and this is also the case with the North 

 American form C. parcus, Herrick, of which I have had specimens for examination 

 kindly sent to me by Prof. Forbes From the 3 preceding species it is easily 

 distinguished by its slender elongated body, rather resembling in this respect some 

 of the succeeding species, especially C. pulcliellus and C. bisetosus. It is, how- 

 ever, well distinguished also from these species by several well-marked characters, 

 as shown hereafter. 



Occurrence The present species is found rather commonly throughout 

 the whole country in shallow pools and ditches. Especially early in the spring 

 it abounds in nearly all the ponds round Christiania, but is also met with, 

 though not so frequently, at other seasons. A smaller variety is often found 

 having the caudal rami somewhat shorter, but otherwise agreeing with the typi- 

 cal form. 



Distribution. Throughout Europe, Central Asia, New Siberian Islands, 

 Ceylon, North America. 



24. Cyclops robustus, G. 0. Sars. 



(PI. XXVI). 



Cyclops robustus, G-. 0. Sars, 1. c., p. 36. 

 Syn.: Cyclops brevispinosus, Herrick. 



Srjecific Characters. Female. Body considerably more robust than in 

 the preceding species, with the anterior division rather dilated and oval in form, 

 greatest width exceeding half the length and occurring about in the middle. 

 Cephalic segment very large and evenly rounded in front. Lateral parts of 



