213 

 109. Cytherura undata, G. O. Sars. 



(PI. XCIX, fig. 1). 



Cytherura undata, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 75. 

 Syn: Cytherura humilis, Brady. 

 ,, pumila, Norman. 



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

 oval subrhomboid in shape, a little higher in front than behind, greatest height 

 exceeding somewhat half the length, dorsal margin quite evenly arched throug- 

 hout, ventral margin nearly straight and terminating behind in an angular 

 corner, anterior extremity rather obliquely rounded, posterior obliquely trun- 

 cated below and forming about in the middle a very short and blunt protu- 

 berance; seen dorsally, oblong oval in outline, with the greatest width not 

 nearly attaining half the length, side-edges scarcely at all curved and somewhat 

 waved, anterior extremity tapering to a blunt point, posterior abruptly con- 

 tracted to a short conical prominence. Valves of rather firm consistency and 

 very little pellucid, surface much uneven, exhibiting a peculiar undulate or 

 wrinkled appearance, the wrinkles being only few in number and rather irregu- 

 larly arranged, forming in the posterior part of the shell more or less elevated 

 rounded protuberances. Anterior antennae with the terminal part rather coarse, 

 last joint however very small. Posterior antennae with the dividing suture of 

 penultimate joint located somewhat above the middle. Legs not much pro- 

 longed, last pair with the 1st joint of the terminal part shorter than the other 

 2 combined. 



Male of rather smaller size than female and having the shell much nar- 

 rower, with the dorsal margin quite straight in the middle. Copulative appen- 

 dages with the basal part obliquely oval in shape and sending off below 2 

 unequal processes, the anterior one the larger and drawn out to a narrow 

 slightly recurved lappet, copulatory string very coarse and curled up in a dense 

 spiral; terminal part oblong quadrangular in form, being almost transversely 

 truncated at the end. 



Colour of shell opaquous bluish gray. 



Length of adult female 0.52 mm. 



Remarks. This is an easily recognisable species, being in particular 

 distinguished by the peculiarly undulated or wrinkled surface of the valves, to 

 which character indeed the specific name proposed alludes. 



Occurrence. I have taken this form occasionally in several places on the 

 Norwegian coast, from the Christiania Fjord up to the Lofoten islands. All 

 the specimens were found in the laminarian zone on a sandy bottom. 



