183 



gently arched and joining the posterior one without any intervening angle, 

 ventral margin distinctly sinuated in front of the middle and slightly convex 

 behind, anterior extremity broadly rounded and somewhat bowed below, posterior 

 narrower and obliquely truncated, with the lower corner somewhat exerted, but 

 obtuse at the end; seen dorsally, oblong ovate in outline, with the greatest 

 width behind the middle and somewhat less than half the length, anterior 

 extremity pointed, posterior more obtuse. Surface of valves evenly convex and 

 of a somewhat dull appearance, being all over conspicuously pitted and clothed 

 at each extremity with closely set rather coarse hairs. Both pairs of antennae 

 very robust, the anterior ones with the last joint about half the length of the 

 preceding one, the posterior ones with the fagellum scarcely extending to the 

 middle of the terminal part. 



Male of about same size as the female, but having the shell considerably 

 narrower and more tapered behind. Copulative appendages with the terminal 

 part produced in front to an acute triangular lappet, and crossed inside by 2 

 anteriorly-verging processes issuing from the basal part, the lower one highly 

 chitinised and sharply pointed at the tip, the upper terminating in a narrow, 

 slightly upturned lobule, which projects somewhat beyond the edge in front. 



Colour of shell dark fuscous, with a distincte violaceous tinge, marginal 

 zone lighter; limbs bright yellow. 



Length of adult female 0.70 mm. 



Remarks. The present form resembles somewhat in the general shape 

 of the shell Cythere lutea, but is at once distinguished by the very different 

 sculpture of the valves and, when examined in the fresh state, also by the 

 rather dissimilar colour. It is a true member of the genus fiemicythere, as 

 here defined, agreeing in all structural details with the several species of this 

 genus described in the sequel. 



Occurrence. The species occurs not unfrequently off the Norwegian coast, 

 from the Christiania Fjord to Finmark in the laminarian region. 



Distribution. British Isles, Iceland, Bay of Biscay. 



Fossil. Norway, British Isles. 



85. Hemicythere emarginata, G. O. Sars. 



(PI. LXXXV, fig. 1.) 

 Cythereis emarginata, G. O. Sars. Oversigt af Norges marine Ostracoder, p. 38. 



Specific Characters. Female. Shell, seen laterally, short subreniform in 

 shape, somewhat higher in front than behind, greatest height considerably 

 exceeding half the length, dorsal margin gently arched in the middle and 



