215 



Remarks. This is a somewhat anomalous species, differing from the other 

 known forms notably, both in the structure of the shell and in that of some 

 of the appendages, though apparently referable to the present genus. 



Occurrence. Some few specimens of this remarkable form were obtained at 

 Korshavn, south coast of Norway, from a depth of 20 30 fathoms, muddy sand. 



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



111. Cytherura clathrata, G. O. Sars. 

 (Pi. C, fig. 5). 



Cytherura clathrata, G. O. Sars, Oversigt af Norges marine Ostracoder, pag. 77. 



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

 rounded subtrigonal i shape, greatest height in the middle and almost attaining 

 2 /3 of the length, dorsal margin boldly arched, and sloping rather steeply both 

 in front and behind, ventral margin not at all sinuated, being distinctly convex 

 throghout, anterior extremity rather oblique and narrowly rounded below, with 

 the edge divided into 3 4 short and broad tooth-like projections, posterior 

 extremity produced about in the middle to a comparatively short protuberance, 

 well defined below by a distinct sinus; seen dorsally, oblong oval or 

 somewhat lanceolate in outline, with the greatest width behind the middle 

 and about equal to half the length, anterior extremity gradually tapered to a 

 sharp point, posterior abruptly contracted at the end, to form a narrow conical 

 prominence. Valves of rather firm consistency and remarkably unequal, the 

 right one considerably overlapping the left along the dorsal face, and having 

 the hind protuberance conspicuously narrower, each valve provided near the 

 ventral face with a well-marked longitudinal crest appearing, in the dorsal aspect 

 of the shell, as a thin border flanking the sides, posterior part of the shell 

 with 2 superposed rounded protuberances on each side; surface roughly reti- 

 culated, the meshes being defined by distinctly elevated ribs, one of these 

 ribs, running along the middle of each valve being particularly strong, inner 

 duplicatures quite simple, emarginated both in front and behind. Anterior 

 antennae comparatively slender, with the 2 middle joints of the terminal part 

 nearly equal in length, last joint about half as long as the preceding one. 

 Posterior antennae much coarser, with a well marked oblique suture of the 

 penultimate joint a little above the middle, apical claws more slender than in 

 the other species. Legs of moderate length, last pair with the 1st joint of the 

 terminal part about as long as the other 2 combined. 



