POLYCOPE. 



219 



Family 5— POLYCOPID^. 



Genus 1 — Polycope, G. 0. Sars. 



Valves rounded, ventricose, thin, and fragile, corneo-calcareous. Forehead having 

 no tentacle, but in its place two ciliated setas. Upper antennse three-jointed, last joint 

 short, terminal setae long and slender; tenninal rami of the lower antennae unequal, one 

 many -join ted, of structure very similar to that of Cypridina, the other shorter and three- 

 jointed. Lower extremity of mandibles strongly inflexed, armed with a few small acute 

 teeth ; palp biarticulate, first joint stout, bearing externally a short, bisetose, branchial 

 appendage ; last narrow, beset with long plumose setae. Incisive portion of the first pair 

 of jaws small, forming a simple setiferous lobe ; palp very large, four-jointed, two-branched, 

 second joint bearing externally a long, narrow, and obsoletely biarticulate branch, which 

 is terminated by long setae. Second pair of jaws membranaceous, three-jointed ; penul- 

 timate joint bearing externally a small branch which terminates in a single seta ; furnished 

 at the base with a large branchial plate. Postabdominal plates short, posterior margin 

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

 ming actively like the Lynceidae. 



Polycope orbicularis, G. 0. Sars. Plate XII, figs. 22, 23. 



1865. Polycope orbicularis, G. 0. Sars. Overs. Norg. mar. Ostrac, p. 122. 

 1868. — — Brady. Monog. Rec. Brit. Ostrac, p. 471, pi. x.xxv, 



figs. .53 — .57. 



Shell subspheroidal ; as seen from the side, almost circular, somewhat flattened on 

 the dorsal margin. Seen from above, ovate, tapering evenly to each extremity, greatest 

 width situated in the middle, equal to more than half the length. Surface of the shell 

 finely and closely punctate, and mostly divided by delicate raised ridges into numerous 

 polygonal areolae. 



Diameter, -^nd of an inch. 



There is a good deal of diversity in the surface-ornament of this species. The 

 specimens from Dalmuir, one of which is figured in our plate, are distinctly areolated, 

 but the puncta are small and faint ; the Paisley specimens, on the contrary, are much 

 more strongly punctate, and others are almost entirely destitute of sculpture of any kind. 



