260 MR. W. PEECT SLADEN OS THE 



series, and form a gradual transition into the spiniform squamu- 

 lation of the plate. Consequent on this arrangement the marginal 

 spines have a short, compact, and almost tufted appearance ; whilst 

 the series form a thick and closely crowded fringe along the ray. 

 The squamules of the inf ero-marginal plates are rather long, flat, 

 and rounded or obtusely pointed at the extremity, and although 

 numerous they are not very closely placed. Three or four 

 more prominent squamules, simulating spinelets, form a line 

 along the aboral margin of the plate, and occasionally similar 

 ones may be found here and there on other parts of the plate. 

 Ventral plates not more than 6-8 present, carrying very small, 

 short, and equal-sized papilliform spinelets, which appear to 

 form a kind of pedicellaria. 



Ambulacral spines short, and forming two series. The inner 

 series, consisting of three spines, short, cylindrical, slightly taper 

 and obtuse, the middle one being more robust, compressed late- 

 rally, geniculated and prominent in the farrow. The outer series, 

 near the middle of the ray, has three spines equal to, or rather 

 longer than, the inner series, more robust, slightly compressed, 

 and obtusely rounded at the tips, running obliquely across the 

 plate, the adoral spinelet often being in the position of a third 

 series. On the inner portion of the ray one or two supple- 

 mentary spinelets may be present, external to the oblique line of 

 three spines above mentioned. 



Mouth-plates elongate, and form a long prominent narrow keel 

 along the line of suture. Upon the keel there is a single line of 

 spinelets on each plate, rather long, robust, compressed, and sub- 

 papilliform ; these are 7-9 in number, and diminish in size 

 aborally. On the outer free margin of the plate there are about 

 8 spinelets — the three innermost, which with the corresponding 

 spinelets of the companion mouth-plate form the comb of spines 

 projecting horizontally over the mouth, are longer than the rest, 

 and are slightly curved inward at their extremities in the direc- 

 tion of the horizontal plane of the mouth-area. The remaining 

 spinelets are much smaller and equal-sized, and their series do 

 not reach beyond a line drawn at right angles through the middle 

 of the median suture-line. 



The armature of the first adambulacral plate beyond the 

 mouth-plates consists of 15 or more pairs of small equal papilliform 

 spinelets, ranged in two parallel lines and apposed to one another, 

 which form a remarkably elegant organ probably of pedicellarian 



