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Show 386 PROF. F. J. BELL O N E C H I N O D E R M S [June 19, a number of intermediate stages wanting, which Mr. Thurston will, I hope, be some day able to fill up. This species is quite distinct from any of the triplacanthid Oreasters known to me. PECTINURA INTERMEDIA. This species stands with P. gorgonia, P. marmorata, and P. stellata1 of Mr. Lyman's arrangement; for it has the disk covered under its granulation with coarse scales, and there are pores between the first and second arm-plates ; but the disk is flat, with the arm compressed from side to side and keeled superiorly, while there are eight arm-spines. Radial shields naked, of moderate size, rather irregularly elliptical in form ; the rest of the disk covered superiorly by a coarse granulation, beneath which are plates of fair size. The arms widest at their insertion, distinctly carinated ; accessory mouth-shields of fair size ; pores between first and second arm-plates only ; near the base of the arms eight spines ; upper arm-plates not broken. Eighteen mouth-papillae, the outermost on either side small; its neighbour the largest of the series; four teeth. Mouth-shields irregularly hexagonal, the adoral edge the shortest; accessory mouth-shields irregularly semicircular in form; side mouth-shields tend to the form of an equilateral triangle; granulated space between mouth-papillae and mouth-shield well-marked. Lower arm-plates at first wider than long; further out they become unequally hexagonal, owing to the encroachment of the side-plates on the adoral edge; the upper arm-plates, near the edge of the disk, are quite three times as wide as they are long; further out their adoral edge becomes encroached on by the side-plates ; the cari-nation is best marked on the proximal half of the arm ; while there are eight arm-spines near the base, there are only six some way out; the spines are always delicate and short; the two lowest are a little longer than the rest, but they are never so long as the side arm-plate. Two tentacle-scales. The disk is, above, of a brownish hue, with yellowish patches and black dots ; the radial shields are lighter, as is also the oral surface. The arms are banded lighter and darker, in sets of four or five ; in the case of the darker bands the most proximal and the most distal plates are a good deal darker than the intermediate three. Diameter of disc 18, 16 millim.; length of arm about 75 from the edge of the disk ; width of arm at disk 4, 3*5 ; height of same 3-5, 3-5. RHINOBRISSUS PYRAMIDALIS. 1 should have less diffidence in assigning two specimens to this species had I been fortunate enough to have been enabled to compare with them the examples in the Liverpool Museum, on which 1 This is the Ophiopinax stellatus of the ' Alert' Report (p. 136). |
