REPORT ON THE OSTEACODA. 1G9 



minated by long setae. Second pair of jaws membranaceous, three-jointed ; penultimate 

 joint bearing externally a small branch which terminates in a simple seta, furnished at 

 the base with a large branchial plate. Post-abdominal plates short, posterior margin 

 shortly digitate, and armed between the segments with acuminate claws. Animal 

 swimming actively like the Lynceidas. 



Very few specimens referable to this genus have been observed in the Challenger 

 dredgings. These belong to three species, two of which are undescribed. 



1. Polywpe orhicularis, G. 0. Sars. 



Polyeope orhicularits, G. 0. Sars, Oversigt af Norges marine Ostracoder, 1865, p. 122. 

 Polycope orlicidaris, Brady, Monog. Eeceut Brit. Ostrac. 1868, p. 471, pi. xxxv. ligs. 53-57. 

 Polyeope orhicularis, Brady, Crosskey, and Eobertson, Mouog. Post-Tertiary En torn., p. 219, 

 pi. xii JBgs. 22, 23. 



Shell of the female, as seen from the side, subcircular, greatest height in the middle, 

 and slightly smaller than the length ; anterior margin slightly narrowed and produced, 

 posterior evenly rounded, dorsal and ventral margins boldly convex ; outline, as seen 

 from above, ovate, tapering ecjually to each extremity, greatest width in the middle, and 

 somewhat exceeding half the length. Valves finely punctate, and divided by fine 

 reticulating ribs into numerous polygonal areolae ; colour pale yellow, marked with 

 patches of a darker reddish colour. Basal joint of the anterior antennae longer than the 

 two others combined, densely hairy on the anterior margin, and provided with a short 

 seta, last joint ending in five long, slender setae ; one branch of the posterior antenna 

 eight-jointed, its last seven joints short and subequal ; second branch three-jointecl, its 

 first joint longer than the united lengths of the two following, and bearing eight long, 

 partially-ciliated seta3. Mandibles divided at the apex into five teeth, the outermost of 

 which is much the longest ; palp shorter than the mandible itself, its last joint equal in 

 length to the basal joint, and bearing seven ciliated setae. Secondary branch of the 

 anterior maxillae reaching a little beyond the apex of the palp, and terminating in about 

 eight very long and slender setag. Branchial plate of the posterior maxillae narrow, 

 elliptical, bearing sixteen ciliated marginal setae. Post-abdominal plates armed with six 

 finely-cUiated claws, decreasing gradually in length backwards ; behind them two short 

 setae. Posterior margin of the abdomen bearing three branches of short hairs. Male 

 unknown. Length, l-85th of an inch ('S mm.). 



Though specimens which may fairly be referred to this species have been met with in 

 several of the Challenger dredgings, none of them are good or well developed, and they 

 have therefore not been figured, while, as regards some of them, doubts may perhaps be 

 entertained as to their specific identity. The species is well known in the seas of Northern 

 Europe, especially in those of Great Britain and Norway ; I have seen specimens also 

 from Spitzbergen ; and it occurs somewhat sparingly in the Post-Tertiary deposits of 



(ZOOL. CHALL. EXP. PAET HI. — 1880.) C 22 



