40 



Remarks This is an easily recognisable species, though, according to 

 the structure of the several appendages, it seems to be referable to the same 

 group as the 4 preceding species. It is, however, at once distinguished from 

 them by its much larger size, the 14-articulate anterior antennae, the peculiar 

 shape of the genital segment, and the long and slender caudal rami. The C. 

 qvadricornis of Koch seems to be this species; but as the name qvadricornis is 

 a collective one, it cannot be maintained. The form recorded by Brady as C. 

 insignis is scarcely that species. 



Occurrence. I have taken this form in great numbers early in the spring 

 from ponds near Christiania. Later in the summer it was not observed. 



Distribution. Sweden (Lilljeborg), Germany (Schmeil), Bohemia (Pric). 



20. Cyclops vulgaris, Koch. 



(PI. XXII). 



Cyclops rulgaris, Koch, Deutschlands Ornstaceen, Myriopoden und Arachniden, Heft 21, Tab. 4. 

 Syn.: Monoculus qvadricornis viridis, Jnrine. 

 Cyclops viridis, Fischer, 

 brevicornis, Clans. 



Specific Characters. Female. Body comparatively robust, with the anterior 

 division rather dilated and broadly oval in form, greatest width considerably 

 exceeding half the length Cephalic segment very large and broadly rounded in 

 front. Lateral parts of penultimate trunk-segment of same appearance as those 

 of the 2 preceding segments. Last trunk-segment only slightly produced laterally. 

 Tail scarcely exceeding half the length of the anterior division ; genital segment 

 moderately dilated in front and gradually narrowed behind. Caudal rami scarcely 

 longer than the last 2 segments combined, and only very slightly diverging, 

 without any dorsal keel, but with the inner edge finely ciliated; seta of outer 

 edge not very far from the end, middle apical setae rather elongated, the inner 

 one attaining half the length of the body; seta of inner corner more than 

 twice as long as that of the outer. Anterior antennas not very slender, being 

 scarcely longer than the cephalic segment, and composed of the usual number 

 of joints (17). Posterior antennae with the terminal joint longer than the penulti- 

 mate one. Anterior maxillipeds more strongly built than in the preceding species. 

 Natatory legs likewise rather strong; terminal joint of outer ramus in all of them 

 with only 2 spines outside, inner edge of same joint in the 1st pair with only 

 2 setae, in the other pairs with 3 seta? ; apical spines of inner ramus in 4th pair 

 of almost equal size. Last pair of legs with the proximal joint unusually broad 

 and conically produced outside, distal joint very small, with the lateral spine 

 extremely minute and rudimentary. Ovisacs large, fusiform in shape, and con- 



