167 



Gen. 35. Cythere, O. Fr. Muller 1785. 



Generic Characters. Shell slightly compressed and more or less reniform 

 in shape, with the surface evenly convex, without any projections or spines. 

 Valves somewhat unequal, with the inner duplicatures rather broad; marginal 

 zone well marked and crossed by more or less crowded pore-channels, edges 

 smooth, Hinge with the closing teeth in front and behind well developed. 

 Eyes widely appart. Antennae robust; the anterior ones with the terminal part 



triarticulate, middle joint elongate and armed in front with 2 stout claw-like 





 spines; the posterior ones with the apical claws rather short and stout, flagellum 



well developed in both sexes. Vibratory plate of mandibular palp much reduced. 

 Maxillae with the masticatory lobes more or less produced, palp comparatively 

 narrow. Legs rather strong and only slightly increasing in length posteriorly, 

 anterior border of basal part with 2 unequal setae. Caudal lamellae edged with 

 3 bristles, 2 apical and 1 lateral. Copulative appendages of male with the 

 terminal part of various shape in the different species. 



Remarks. The limits of this genus, which originally comprised all the 

 Cytheridae, have in recent time been considerably succincted by the removal 

 of a number of the forms into distinct genera. But even in the restriction now 

 generally adopted, this genus comprises a vast number of species, both fossil 

 and recent. As however these species, almost in every case, have been examined 

 only from the shell, it is very difficult to decide their true mutual relationship. 

 Some of them look indeed so very different from the type of the present genus, 

 that I am much inclined to believe that they are not at all congeneric; but 

 this cannot properly be settled, except by a careful examination of the limbs. 

 In the present Account I have felt justified, on the base of a thorough ana- 

 tomical examination, to establish 4 new genera for comprising some species 

 hitherto considered as true members of the genus Cythere. In the restriction 

 here adopted, the present genus is represented in the Fauma of Norway by 

 only 3 species, to be described below. 



73. Cythere lutea, O. Fr. Muller. 



(PI. LXXVII.) 



Cythere lutea, O. Fr. Muller, Entomostrac.i, p. 65, PI. VII, figs 3, 4. 

 Syn: Cythere reniformis, Baird. 

 . setosa, Brady. 



Specific Characters. Female. Shell rather compressed, seen laterally, 

 short reniform in shape, greatest height in the middle and almost attaining 3 /5 



