470 PROCEEDINGS OF THE NATIONAL MUSEUINI vol. >*.; 



Genus PORANIOPSIS Perrier 



PORANIOPSIS JAPONICA new species 

 FiGUKr; 5H ; Plates 55, 5i; 



roraniop-^i.f sp. Fishkb, U. S. Nat. Mas. Hull. 7(». pr. 1. p. lit>4, I'.tll (off Hou-shn. 

 Jaijau, ISi' fathoms). 



D'wghosis. — Ditfering t'roiii I*, hijiata (Fi.sliei) in liaving u larger 

 disk, rays broader at base, a decidedly hroadci- abactinal area with 

 more iiunierous a})actinal spineji. numerou.s (lelicate tliornv spinelets 

 immersed in the thick meinbraiie of papular areas, more widely 

 spaced inferomargiiial spines, adambidacral spines without well- 

 marked groove. K==77 mm, r^-88 mm, R = :^r, br^40 nnn. 



Description. — When the animal is viewed ilirectly from above the 

 superomarginal series of spines curves downward on the sides of ray 

 and marks the border of the actinal area. In inffdta it is higher on 

 side of ray and fairly straight. As a result the abactinal area i.s 

 broader in japonica. Including the first superomarginal spine of 

 each side, one can count 10 to 1'2 spines across base of ray, wherea.< 

 in inflata the number is 5 to 8. Tiiis means that the dorsolateral 

 spines are more jmmerous in japonica; and as the {)hotograph shows, 

 neither they nor the median radial spines form regular longiseries. 

 These spines are about as long as in iivflata of comparable size, that 

 is, fiom ;') to 6 nnn. the apparent height bein<r somewhat enhanced 

 by the ciMitral convexity of the lobed plate upon which they stand. 

 The skeleton forms well-marked rounded ridges coi meeting the 

 spines and outlining the large papular areas with iheii- papulae. 

 The skin is rather thicker than in itiiJata and is traver.sed by mim- 

 erous anastomosing channels. On the papular areas are low dermal 

 papillae smaller than the papulae, in which are delicate, slender 

 spinelets with tliorny sharp projections all along the sides. These 

 spinelets are 0.4 to 0.55 mm long and 0.15 mm thick including thorns.^ 

 which are 0.0*27 nun long. Thesi' are in the outer layer of the integu- 

 ment. Usually independent of the dernuil spinelets, in a lower layer 

 of the integument, are more numerous small plates. 0.12 to 0.6 mm 

 in diameter. The smallest are scarcely more th:in o tiers of very 

 open irregular meshwork, but the largest are thick and opa(|ue under 

 higli power. It may be that the thorny spinelets were originally con- 

 nected each with a platelet and became dissociated by a swelling <»f 

 the dermis in alcohol, but there are more platelets than spinelets. 

 The latter resemble the dermal spinelets of Porania qldbra Sla<leu 

 and may prove to be as variable in nimiber as in that species. They 

 have not been detected in in-flata and echinaster but innnediately 

 suggest the thortiy dermal s])inelets of Pornninpais mint (de Ijoriol). 



