210 



not nearly attaining half the length, dorsal margin evenly arched throughout, 

 without any angular bend either in front or behind, ventral margin very slightly 

 sinuated in front of the middle and only little bowed behind, anterior extremity 

 somewhat irregularly rounded, being obtusely produced in the middle, posterior 

 gradually narrowed to a very prominent protuberance located slightly below 

 the longitudinal axis of the shell; seen dorsally, broadly oval in outline, with 

 the greatest width a little behind the middle and exceeding somewhat half 

 the length, lateral faces flanked by an evenly curved pellucid border, both 

 extremities conically produced at the end, the posterior somewhat more ab- 

 ruptly contracted than the anterior. Valves rather thin and pellucid, each pro- 

 vided near the ventral face wiih an elevated thin longitudinal rib, very con- 

 spicuous in the dorsal or ventral aspects of the shell; surface perfectly smooth, 

 without any obvious sculpture; central area of valves much reduced in extent. 

 Anterior antennae with the joints of the terminal part successively diminishing 

 in size, the last very small, scarcely attaining half the length of the preceding 

 joint. Posterior antennae with the dividing suture of penultimate joint located 

 nearly in the middle. 



Male not observed. 



Colour of shell not yet ascertained. 



Length of adult female 0.50 mm. 



Remarks. The above-described form is easily recognisable by the greatly 

 produced protuberance of the hind extremity, as also by the very conspicuous 

 lateral crests. The shape of the shell differs also somewhat from that in the 

 other species, both as seen laterally and dorsally. 



Occurrence. A few female specimens of this form were found among 

 some Ostracoda collected at Korshavn, south coast of Norway, from depths 

 ranging from 20 to 40 fathoms, muddy sand. Norman has also recorded the 

 species from 2 localities on the west coast. 



Distriba tion. British Isles, Holland. 



107. Cytherura acuticostata, G. O. Sars. 



(PI. XCVIII, fig. 1). 

 Cytherura acuticostata, G. O. Sars, Oversigt over Norges marine Ostracoder, p. 76. 



Specific Characters. Female. Shell rather tumid, seen laterally, shor 

 subquadrangular in shape, equally high in front and behind, greatest height 

 exceeding half the length, dorsal margin nearly straight in the middle and 

 gently curved behind, joining the anterior edge without any obvious angle in 



