REPORT ON THE ASTEROEDEA. 41 



6. Pontaster teres, n. sp. (PI. IX. figs. 5 and 6 ; PI. XII. figs. 11 and 12). 



Rays five. R = 42 mm. ; r = 7'5 mm. E > 5 - 5 r. Breadth of the ray at the base, 

 8 mm. 



Rays elongate, narrow, subdepressed ; not very broad at the base, tapering throughout 

 up to the extremity. Interbrachial arcs well-rounded. Abactinal surface subplane, sloping 

 slightly from the centre of the disk to the extremity of the rays. Actinal surface flat 

 and level. 



The paxilla3 of the abactinal surface are large, ornate, and uniform, but decrease in 

 size as they proceed along the ray. The large ones on the disk have a broad tabulum, 

 bearing a double circlet of short papilliform spinelets, surrounding a central, robust, sub- 

 conical, obtusely pointed spinelet, three or four times their length and thickness. There 

 may be sixteen or even more spinelets in the outer circlet and about half that number in the 

 inner circlet, which are slightly more robust, often subconical, and sometimes appearing 

 subgranuliform, sometimes disposed so as to give the appearance of several larger central 

 spinelets, one of which, however, is usually longer than the rest. On the outer half of the 

 ray, only the outer circlet of papilliform spinelets is usually present, with a smaller 

 number of spinelets, which are very short, obtuse, and subgranuliform in appearance. The 

 embryonic basals, though quite inconspicuous, may be traced ; their paxillae being rather 

 larger than the rest. 



The supero-marginal plates, twenty-seven in number from the interradial line to the 

 extremity, form a comparatively broad, but roundly bevelled margin to the rays when 

 viewed from above. On the inner half of the ray tbe breadth is greater than the length, but 

 towards the extremity the proportions are reversed. The plates are slightly convex, and the 

 transverse sutures between them are very oblique, passing from within outwards adorally ; 

 the obliquity increases on the outer part of the ray, and the plates there have an oval appear- 

 ance in consequence of their convexity and increased length. The surface of the plates is 

 covered with numerous very short, subtapering or obtusely conical, papilliform thornlets, 

 those on the centre of the plate, especially near the inner abactinal margin, being coarser 

 than the rest. Most of the plates bear a single, delicate, tapering spinelet about 1 to 

 1"5 mm. in length. Perhaps normally all were thus armed, but many are absent in the 

 specimens under notice, in one case apparently due to abrasion. 



The infero-marginal plates alternate with the superior series. They are as high as, 

 or even higher than, broad on the inner half of the ray. Their whole surface is covered 

 with numerous closely placed, cylindrical or subclavate, delicate spinelets, which, though 

 very minute, are much longer than those covering the supero-marginal plates. Each 

 plate bears a delicate, tapering, sharply pointed lateral spine, the longest a little longer than 

 3 mm., and behind this normally one, or occasionally two, similar but smaller spinelets. 



The adambulacral plates have an extensive acute angular projection into the furrow, 

 which causes them to have a very broad appearance. Their armature consists of : — (1.) A 



(ZOOL. OHALL. EXP. PABT LI. 1S87.) 6 



