_249_ 



Remarks. This genus has been established by G. W. Miiller, to include 

 5 species found by him in the Gulf of Naples, and was chiefly characterised 

 by the peculiar beak-like appearance of the oral cone and by the great 

 reduction of the mandibles. On the closer examination of the forms of the 

 present subfamily found off the Norwegian coast, I have been enabled to 

 state, that some northern species hitherto recorded by Brady as members 

 of the genus Paradoxostoma, in reality are referable to the present genus. 

 3 such species will be described in the sequel. 



137. Paracytherois arcuata, (Brady). 



(PI. CXIII, fig. 1). 



Paradoxostoma arcuatum, Brady, Mon. Brit. Ostracoda, p. 461, PI. XXXV, figs. 37, 38. 

 Syn: Paracytherois rara, G. W. Miiller. 



Specific Characters. Female. Shell, seen laterally, oblong bean-shaped, 

 not unlike that of Sclerochilus contortus, greatest height somewhat behind the 

 middle and not nearly attaining half the length, dorsal margin forming a rather 

 even arch sloping somewhat more steeply behind than in front, ventral margin 

 rather deeply sinuated in front of the middle and gently convex behind, 

 anterior extremity somewhat deflexed and evenly rounded off at the end, 

 posterior terminating below in an obtuse corner; seen dorsally, very narrow, 

 lancet-shaped, with the greatest width not even attaining 1 U of the length; 

 both extremities sharply pointed, the anterior somewhat narrower than the 

 posterior. Valves thin and pellucid, with the surface smooth and polished, 

 marginal zone well marked and rather broad along the ventral face, pore- 

 channels very few in number, but easily observable. Anterior antennae with 

 the distal segment of the basal part long and narrow, almost cylindrical in 

 shape, and without any setae; terminal part scarcely longer than this segment, 

 with the joints very unequal in* size. Posterior antennae with the dividing 

 suture of the penultimate joint located about in the middle. Legs not much 

 prolonged, last pair with the 1st joint of the terminal part considerably shorter 

 than the. other 2 combined. 



Male resembling the female both in size and in the general shape of 

 the shell. Copulative appendages with the basal part obpyriform in outline, 

 terminal part consisting of 2 subequal curved spines. 



Colour of shell whitish, pellucid. 



Length of adult female 0.55 mm. 



Remarks. The above-described form agrees pretty well with the descrip- 

 tion and figures given by Brady of his Paradoxostoma arcuatum, and I am 



31 Crustacea. 



