REPORT ON THE ASTEROIDEA. 41 
6. Pontaster teres, n. sp. (Pl. IX. figs. 5 and 6; Pl. XII. figs. 11 and 12). 
Rays five. R=42mm.;r=75mm. R>5‘5r. 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 paxille 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 
suberanuliform, 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 paxillz 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 the 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. Hach 
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 ancular projection into the furrow, 
which causes them to have a very broad appearance. Their armature consists of :—(1.) A 
(Z0OL. OHALL. EXP.—PaRT LI.—1887.) 6 
