235 



128. Bythocythere constricta, G. O. Sars. 



(Pi. CVIII, fig. 1). 

 Bythocythere constricta, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 85. 



Specific Characters. Female. Shell much less compact than in the pre- 

 ceding species, seen laterally, oblong subquadrangular in shape, somewhat 

 higher behind than in front, greatest height scarcely exceeding half the length, 

 dorsal margin perfectly straight and horizontal, being somewhat angularly bent 

 hoth in front and behind, ventral margin slightly sinuated anteriorly and con- 

 siderably bowed behind, anterior extremity obtusely rounded off, posterior pro- 

 duced, considerably above the middle, to a well-marked rather broad protuber- 

 ance obliquely truncated at the end; seen dorsally, irregularly fusiform in 

 outline, exhibiting, somewhat in front of the middle, a very conspicuous deep 

 constriction, side-edges both in front and behind the constriction abruptly 

 bowed, greatest width somewhat less than the height, anterior extremity 

 obtusely pointed, posterior gradually tapered to a narrow conical prominence. 

 Valves very thin and pellucid, with the lateral expansions rather slight, surface 

 slightly rugulose and faintly marked with small scattered pits, edges of valves 

 quite smooth. Eyes wholly absent. Antennas of a structure very similar to 

 that in the preceding species. Legs however comparatively more slender and 

 prolonged, last pair with the 1st joint of the terminal part about the length 

 of the other 2 combined. 



Male of smaller size than female, but resembling it in the general shape 

 of the shell, though having the posterior part somewhat broader, as seen 

 laterally. Copulative appendages of a structure very similar to that in the 

 preceding species. 



Colour of shell uniformly whitish pellucid. 



Length of adult female 0.80 mm. 



Remarks. Though closely agreeing with the preceeding species in the 

 structure of the several appendages, the present form is at once distinguished 

 by the rather different appearance of the shell, and more particularly by its 

 very conspicuous mediate constriction, as seen dorsally, a character which 

 indeed has given rise to the specific name proposed. 



Occurrence. This form was originally described from a single female 

 specimen taken af the islands Bollaerene in the lower part of the Oslo Fjord 

 at a depth of 30 40 fathoms, soft clayish bottom. I have subsequently also 

 met with it occasionally in some other places on the Norwegian coast, at 

 similar depths. 



