192 



tubercles of the valves. Anterior antennae with the terminal part distinctly 

 4-articulate, last joint more or less prolonged. Posterior antennae with the 

 apical claws rather slender; flagellum poorly developed in both sexes, with 

 the distal part of a remarkably weak consistency. Mandibles with the cutting 

 part less strong than in Hemicythere, palp having the terminal joint much 

 prolonged and curved; vibratory plate rather fully developed, being fringed 

 with 5 setae, 3 apical and 2 lateral, one of the latter rudimentary. Maxillae 

 about as in Hemicythere. Legs rather slender. Caudal lamellas conical in 

 shape, with 2 rather unequal apical setae and one lateral. Copulative appendages 

 of male of somewhat varying shape in the different species. 



Remarks. This genus was established as early as the year 1849 by Jones, 

 to comprise some of the fossil Cytheridce examined by him, in which the 

 shell exhibited a particularly rough and spiny surface. The close relationship 

 of this genus to Cythere was stated by the present author, on examining the 

 limbs in some recent species, though a few differences were found chiefly 

 relating to the structure of the flagellum of the posterior antennae. On that 

 reason the genus was supported by me, as also subsequently by G. W. Miiller, 

 but was taken by both of us in a much wider sense than done by Jones. 

 Brady however did hot at all admit this genus,, which he combined with 

 Cythere. In the present account the extent of the genus has been consider- 

 ably limited by the establishment of the new genus Hemicythere, the species 

 of which were formerly included in Cythereis. The chief differences between 

 these 2 genera are found in the structure of the anterior antennae and of the 

 mandibles. Another characteristic difference has also recently been stated 

 relative to the flagellum of the posterior antennae, which in the present genus 

 is very poorly developed not only in the female, but also in the male. 5 

 species referable to this genus will be described in the sequel. 



93. Cythereis tuberculata, G. O. Sars. 



(PI. LXXXVIII). 

 Cythereis tuberculata, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 37. 



Specific Characters. Female. Shell, seen laterally, oblong subclavate 

 shape, gradually tapered behind, greatest height quite in front and only slightly 

 exceeding half the length, dorsal margin distinctly angular in the ocular region 

 and sloping behind at nearly a straight course, ventral margin very slightly 

 sinuated in the middle and curving gently upwards behind, anterior extremity 

 broadly rounded off, posterior much narrower and obtusely blunted, upper 

 corner obtuse, lower rounded off; seen dorsally, somewhat irregularly oblong 



