57 



Remarks. This form, the smallest of all our Cyclopses. has been con- 

 founded by several authors (Rehberg, Daday, Lande, Richard) with ('. <l'i<ti>hmi'H* 

 Fischer, from which it differs in many essential points, being much more nearly 

 related to C. varicans. From this latter species it may be easily recognised by 

 its much smaller size, the shorter and only 1 1 -articulate anterior antenna: 1 , and 

 the different structure of the caudal setae, finally by the peculiar colouring of the 

 body when alive. 



Occurrence. I have only found this form quite occasionally in small 

 grassy ponds near Christiania. In spite of its small size, it may be readily 

 detected, owing to its peculiar and beautiful colour, which character indeed has 

 given rise to the specific name proposed. 



Distribution. Sweden (Lilljeborg), Germany (Sehmeil), Hungary (Daday), 

 Poland (Lande), France (Richard). 



Gen. 13. MeSOCyClOpS, U. O. Sars, n. 



f 



(Icncrlc Characters. Body more or less slender, with the anterior division 

 generally rather tumid, the posterior very slender. Epimeral parts of the trunk- 

 segments scarcely prominent laterally and, as a rule, not visible in the dorsal 

 aspect of the animal. Last trunk-segment very small, not produced laterally. 

 Genital segment in female rather elongated and very little dilated in front. Caudal 

 rami of moderate length or very short, with all the apical setse generally well deve- 

 loped. Anterior antennae slender and elongated, generally 17-articulate. Posterior 

 antennae likewise slender, with the apical setse long and curved. Maxillipeds 

 rather fully developed. Natatory legs, as a rule, with both rami 3-articulate; 

 terminal joint of outer ramus in all pairs with only 2 spines outside, its inner 

 edge carrying in the 1st pair 2, in the other pairs 3 setae; terminal joint of inner 

 ramus unusually prolonged, especially in the posterior pairs. Last pair of legs 

 very small and generally biarticulate, distal joint carrying 2 slender subequal setse. 

 Seminal receptacle in all the species of a very characteristic form, anterior part 

 short, bilobular, posterior greatly prolonged, tongue-shaped. 



Remarks. This new genus answers to the group of Cyclopses distinguished 

 by Dr. Schmeil as the "Leuckarti group". The species included in this group 

 differ conspicuously in their external appearance from the more typical Cyclopses 

 described in the preceding pages, and more resemble those belonging to the next 

 genus, Pachycy clops, with which they also agree in the unusually slender form of 



s Cn.stacea. 



