196 



seen in the ventral aspect of the shell, each series containing 6 8 spines 

 successively increasing in size posteriorly. Flagellum of posterior antennae very 

 little longer than in female. Copulative appendages with the basal part slightly 

 projecting below, terminal part subtriangular in shape, obtusely produced both 

 in front and behind. 



Colour of shell whitish, with a slight yellow tinge, but in most cases 

 appearing much darker owing to muddy particles adhering to the numerous 

 spines on the surface of the shell; limbs bright yellow. 



Length of adult female amounting to 0.92 mm., of male to 0.95 mm. 



Remarks. This form was first recorded by Norman as a species of the 

 genus Cythere, and was somewhat later observed by the present author, who 

 described it under the name of Cythereis horrida, the specific denomination 

 alluding to the coarse spinous armature of the shell. It is a true member of 

 the present genus, but easily recognisable from the other species. 



Occurrence. I have taken this form not unfrequently in several places 

 on the Norwegian coast, from the Christiania Fjord up to Finmark. It is 

 generally found in depths ranging from 10 to 50 fathoms, muddy bottom. 



Distribution. British Isles, Iceland, Baffins Bay, Spitzbergen. 



Fossil. Scotland. 



96. Cythereis Jonesi, Baird. 



(PI. XCI.) 



Cythere Jonesi, Baird, Brilish Entomostraca, p. 175, PI. XX, fig. 1. 

 Syn : Cythere fimbriata, Norman. 

 ceratoptera, Bosquet. 



. Cythereis spectabilis, G. O. Sars. 



Specific Characters. Female. Shell, seen laterally, obtusely quadrangular 

 or auriculate in shape, higher in front than behind, greatest heigt exceeding 

 somewhat half the length, dorsal margin angularly produced in the ocular 

 region and nearly straight behind, sloping' gently towards the supero-postea 

 corner, ventral margin scarcely at all sinuated, being even a little conve 

 throughout, anterior extremity broadly rounded, posterior rather narrower and 

 likewise obtusely rounded off; seen dorsally, somewhat lozenge-shaped or 

 trapezoid in outline, widening gradually from before backwards to about the 

 posterior third part of the lenght, whence it abruptly contracts behind, both 

 extremities somewhat blunt at the end. Valves comparatively thin, semipellucid, 

 but armed with a somewhat limited number of very conspicuous spines, pretty 

 regularly arranged; each valve exhibiting laterally, near the ventral face, a well 



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