KEPOET ON THE ASTEROIDEA. 365 



1. Marginaster fimbriatus, n. sp. (PI. LVIII. figs. 4-6). 



Rays five. E = 6 mm.; r=5 mm., including the breadth of the marginal fringe. 

 Thickness about 475 mm. at the apex. 



Marginal contour pentagonal, with the sides slightly incurved and the angles rounded. 

 Abactinal area convex, definitely keeled along the median radial lines, and with the inter- 

 mediate areas slightly hollowed. Actinal area slightly convex, with the intermediate 

 areas slightly hollowed. Margin presenting a sharp thin edge, formed by the iufero- 

 marginal plates, which extend far beyond the supero-marginal plates. Both abactinal 

 and actinal surfaces covered with thick membrane. 



The infero-marginal plates are ten in number on each side of the pentagon, or perhaps 

 twelve if a small comb of spinelets at the radial extremity represents an independent 

 plate. These plates, which are thin and lamelliform, are very large in proportion to the 

 size of the test, are broader than long, and have their free margin curved outwardly and 

 furnished with a comb of five or occasionally six short, flattened, roundly pointed, sub- 

 equal spinelets, which radiate slightly apart, the base line of the series occupying the 

 whole of the curved free margin. The posture of the fans or combs of marginal spinelets 

 is consequently horizontal. On the abactinal surface of the plate is a row of four or five 

 granules, parallel to the margin, and sometimes one, two, or more supplementary granules 

 irregularly placed. The actinal surface of the plate is covered with membrane and bears 

 no granules or spines. 



The supero-marginal plates are entirely hidden by the membrane which covers the 

 whole abactinal surface ; they stand almost vertical and imbricate upon each other slightly 

 at the abactinal or upper end, but are scooped out at the actinal end, so as to leave an 

 interspace between each plate. These plates may bear a few conical robust granules 

 irregularly placed. 



The ambulacral furrows are almost closed. The adambulacral plates are small. Their 

 armature consists of two small, equal spinelets, standing side by side on the furrow margin 

 and quite hidden in the furrow ; and, on the actinal surface of the plate, two much larger, 

 flattened, pointed, and thickly skin-covered spinelets, which are obliquely placed one 

 behind the other ; the innermost one of the pair is directed over the furrow and almost 

 touches or interlocks with the corresponding spine on the opposite side of the furrow, and 

 the outer spine is also directed towards the furrow but is less inclined. Seen superficially 

 the adambulacral armature appears to form two longitudinal and alternating series of 

 spines on each side of the furrow, the innermost or marginal series being at first sight 

 unnoticeable. 



The whole actinal area is covered with membrane and is traversed by indications of 

 faint channels passing from the marginal plates to the ambulacral furrow. The actinal 

 intermediate plates are entirely hidden by membrane, but appear to be comparatively 

 large. The plates adjacent to the marginal plates bear normally a small conical papilliform 



