97 



considerably larger size and by the delicate longitudinal striation of the valves, 

 this latter character having indeed given rise to the specific names proposed 

 by Fischer and Brady. 



Occurrence. I have met with this form occasionally in shallow grassy 

 swamps near Christiania, and in some cases rather abundantly. The animals 

 are very habile swimmers, moving about in the water rather quickly. Male 

 specimens are by no means rare, and are often seen in copulation with 

 the females. 



Distribution. Sweden (Lilljeborg), British Isles (Brady), Germany (Zenker), 

 Switzerland (Kaufmann), Russia (Fischer), North America (Turner). 



31. Cypria opihalmica, (Jurine). 



(PI. XLV, fig. 1). 

 Monoculus opthalmicus, Jurine, Hist, des Monocles, p. 178, PI. XIX, figs 16, 17. 



Syn: Cypris punctata, Koch. 

 Cypris compressa, Baird. 

 Cypris elegantula, Fischer. 



Specific Characters. Female. Shell very short and high, seen laterally, 

 broadly and somewhat irregularly rounded in shape, greatest height in the 

 middle and almost attaining 3 /i of the length, dorsal margin very strongly 

 arched, forming a bold an even curve sloping steeply both in front and behind, 

 ventral margin straight or very slightly sinuated in the middle, both extremities 

 evenly rounded off and somewhat deflexed; seen dorsally, narrow oblong in 

 outline, with the greatest width about equal to 2 /5 of the length, anterior ex- 

 tremity more pointed than the posterior. Surface of valves quite smooth, 

 without any trace of a striation, but all over adorned with dark pigmentary 

 speeks; pellucid border in front and behind more conspicuous than in the 

 preceding species. Caudal rami comparatively broader than in that species and 

 having the dorsal edge in its greater extent fringed with delicate spinules, apical 

 claws moderately strong, the distal one about half the length of the ramus. 



Male, as in the preceding specie?, somewhat smaller than female, with 

 the posterior part of the shell comparatively broader and more bluntly rounded 

 behind. Right prehensile palp of maxillipeds conspicuously expanded distally, 

 with a well-marked conical prominence inside at the base of the thumb, the 

 latter terminating in a spiniform process somewhat swollen at the base; dactylus 

 almost attaining the length of the propodos, and having the inner edge slightly 

 bowed in the middle; left palp resembling in shape that in the preceding 



12 Crustacea. 



