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but recorded it as a new species of the genus Cypris under the name C. 

 bimuricata. 



Occurrence. I have taken this form very abundantly in some small creecks 

 with clear water and rich bottom vegetation, located at the border of the 

 0stensj0 lake near Christiania, and I have also met with it in 2 other localities 

 of our country, viz., at Hamar and at Sandesund. The swimming power of 

 this form is very highly developed, and the animals are almost found in con- 

 stant motion, swimming about in the water with great dexterity. In some 

 cases, especially at sunny weather, they ascend to the very surface, moving 

 below it in a more or less gyrating manner, with the back downwards and 

 the belly in immediate contact with the surface, the boat-shaped ventral area 

 apparently serving as a suspending apparatus for that purpose. This peculiar 

 behaviour of the animal, also described by King in the case of Newnhamia, 

 has indeed given rise to the generic name proposed by Lilljeborg. Male 

 specimens occur in about same number as the females, and are easily 

 recognised from them by the rather different shape of the shell. 



Distribution. Throughout Europe, Central Asia (G. O. Sars), North 

 America (Turner). 



Gen. 15. Cyprois, Zenker, 1854. 



Generic Characters. Shell short and high, somewhat exerted behind, 

 without any sharply defined ventral area, pellucid borders of the waives very 

 conspicuous and closely striated transversally. Eye simple, not divided. An- 

 tennae well adapted for swimming, the posterior ones of normal structur 

 though more slender than usual, penultimate joint not subdivided in either o 

 the sexes, last joint comparatively small, apical claws normally develope 

 Mandibles of usual structure. Maxillae with the outermost masticatory lobe, a 

 in Notodromas, very coarse, and armed with 6 unguiform spines. Maxillipeds 

 provided at the base with a well defined vibratory plate; prehensile palps ir 

 male far less powerfully developed than in Notodromas and less unequal or 

 both sides. Anterior legs of quite normal appearance. Posterior legs with 

 the terminal joint extremely small and partly embraced by the end of the 

 preceding joint; apical setae only 2 in number, the 3rd being replaced by a 

 small dentiform prominence. Caudal rami resembling in structure those ir 

 Notodromas, but having a well defined apical bristle in front of the claws 

 Copulative appendages of male very complicate, with several freely projecting 



