386 PROF. F. J. BELL ON ECHINODERMS [June 19, 



a Du.nber of intermediate stap;es 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, F. marmorata, and P. stel- 

 lata ' of Mr. Lyman's arrangement ; for it has ihe disk covered 

 under its granulation witli coarse scales, and there are pores between 

 the first and second arm-plates ; but the disk is flat, with the arm 

 con)[)ressed from side to side and keeled superiorly, while there are 

 eight arm-spines. 



Radial shields naked, of moderate size, rather irregularly elhptical 

 in form ; the rest of the disk covered superiorly by a coarse granu- 

 lation, 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-papillse, the outermost on either side small ; its neighbour 

 the largest of the series; four teeth. Mouth-shields irregularly 

 hexagonal, tbe adoral edge the shortest ; accessory mouth-shields 

 irregularly semicircular in form ; side mouth-shields tend to the 

 form of an equilateral triangle ; graimlated space between mouth- 

 jjapillae 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-s})ines near the base, there are only six some way out ; 

 the spines are always delicate and short ; the two lowest are a httle 

 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 com- 

 pare with them the examples in the Liverpool Museum, on which 



1 This is the Ophiojpinax stellaius of the 'Alert' Eeport (p. 13C). 



