95 



genus with a new one, I have preferred to record it here under the name by 

 which it has been very recognisably described by Kaufmann and more recently 

 also mentioned by Dr. Aim. The latter author has however questioned its true 

 specific validity, regarding it merely as a variety or subspecies of C. ovum and 

 naming it, in accordance therewith, C. ovum serena. In my opinion the pre- 

 sent form ought to be regarded as a well defined species, differing, as it does, 

 from C. ovum rather conspicuously both in size and in the shape of the shell, 

 and moreover exhibiting some well marked differences in the structural details, 

 as pointed out in the above diagnosis. 



Occurrence. Several specimens of this form, both males and females, 

 were taken, some years ago, in our largest lake, Mjesen, at Hamar. They 

 occurred together with some other Ostracoda in a few fathoms deep, on a 

 muddy bottom overgrown with aquatic plants. 



Distribution. Sweden (Aim), British Isles (Brady), ? Germany (Koch), 

 Switzerland (Kaufmann). 



Gen. 13. Cypria, Zenker, 1854. 



Generic Characters. Shell short and high, but much compressed, with 

 the valves slightly unequal, the left one being the larger and somewhat over- 

 lapping the right at both extremities; pellucid borders well observable. Eye 

 large and conspicuous. Antennae well adapted for swimming, and on the whole 

 resembling in structure those in Cyclocypris, except that the subdivided penul- 

 timate joint of the posterior ones in the male is provided with 2 well-marked 

 sensory spines, as in the Candonides. Mandibular palp with the terminal joint 

 unusually produced. Maxillae with the masticatory lobes much reduced in size, 

 palp however rather large, with the proximal joint somewhat lamellar and 

 bowed behind, distal joint small. Maxillipeds with the vibratory plate per- 

 fectly developed, palp in female simple lash-shaped, in male, as usual, pre- 

 hensile and very unequal on each side, the right one being much more pow- 

 erfully developed than the left. Anterior legs of moderate size. Posterior legs 

 with only a single seta inside the penultimate joint, terminal joint les produced 

 than in Cyclocypris, with the 2 innermost setae very small and subequal, the 

 outermost much prolonged and abruptly reflexed. Caudal rami resembling in 

 structure those in the said genus, but without any armature of the dorsal edge 

 at the base. Copulative appendages comparatively small, terminating in 2 

 juxtaposed narrow lappets. Ejaculatory tubes, as in the preceding genus, with 

 7 whorls of radiating spikes, but having the proximal end bladderformy produced. 



