203 



It is easily distinguished from the preceding species by its much smaller size 

 and rather different shape of the shell. 



Occurrence. The present species is very common on the Norwegian coast, 

 being found rather abundantly everywhere in the littoral zone, and often left 

 in tidal pools. It is one of our smallest Ostracoda, the specimens being only 

 visible to the naked eye as small dark points moving slowly on the bottom 

 or along the algae growing on it. 



Distribution. British Isles, Holland, Fosse de Cap Breton, Bay of Biscay. 



Fossil. Norway, British Isles, Canada 



100. Cyiherura similis, G. O. Sars. 



(PI. XCIV, fig. 2). 

 Cytherura similis, G. O. Sars, Oversigt af Norges marine Ostracoder p. 72. 



Syn: Cytherura propinqva, Brady. 

 ,, Sarsii, Brady. 



Specific Characters. Female. Shell somewhat less compressed than in 

 C. nigrescens, seen laterally, oval subreniform in shape, greatest height some- 

 what exceeding half the length and occurring in the middle, dorsal margin 

 only slightly arched and sloping quite equally to both extremities, ventral 

 margin distinctly sinuated in the middle and somewhat bowed behind, anterior 

 extremity broadly rounded, posterior only very slightly exerted, though exhi- 

 biting in the middle a quite short and obtuse protuberance; seen dorsally, 

 oblong oval in outline, with the greatest width behind the middle, posterior 

 extremity more abruptly contracted than the anterior. Surface of valves nearly 

 smooth, with only fainte trace of a reticulation behind; inner duplicatures 

 comparatively less broad than in the preceding species and more regularly 

 defined inwards. Antennae of a structure very similar to that in the said 

 species; defining suture ofthe penultimate joint of the posterior ones however 

 occurring exactly in the middle. 



Male not yet observed. 



Colour of shell much paler than in C. nigrescens. 



Length of adult female 0.54 mm. 



Remarks. As indicated by the specific name proposed, this form exhibits 

 an appearance somewhat similar to that of C. nigrescens. It is however of 

 much larger size, and differs moreover conspicuously in the shape of the shell, 

 as seen laterally, being in particular distinguished by the comparatively much 

 shorter and blunter protuberance of the hind extremity. 



