REPORT ON THE ASTEROIDEA. 65 
1. Dytaster spinosus, n. sp. (Pl. V. figs. 1 and 2; Pl. IV. figs. 11 and 12). 
Rays five. R= 160-164 mm.; r= 30 mm. R>5r. Breadth of a ray near the 
base (between the second and third supero-marginal plates), 22 mm. 
Rays tolerably elongate, robust, and tapering, more or less depressed, with the lateral 
walls angularly rounded. Interbrachial ares wide and openly rounded. Disk compara- 
tively large and massive. Abactinal area of disk slightly inflated, especially opposite the 
base of the rays, the inflation being continued for a short distance along the abactinal 
surface of the ray, which is at first reoularly convex, but becomes flat before half the 
length is attained, and continues so up to the extremity. Actinal surface of the disk 
prominent at the mouth-angles and sloping thence to the margin; that of the rays 
slightly convex, giving them more or less of a rounded appearance when viewed from 
below. 
The abactinal surface of the disk and rays is covered with small closely crowded paxillz, 
composed of short, cylindrical, papilliform, obtusely tipped, equal-sized spinelets, seven to 
ten in each. Paxille with fewer spinelets are interspersed amongst the large ones; and 
on the outer half of the ray seldom more than three to five spinelets occur, and these are 
reduced to mere papilliform granules. The spinelets in the paxillae upon the disk and 
inner half of the rays stand nearly perpendicular, in little brush-like groups, but are 
so closely crowded in this region that it is often impossible to distinguish the individual 
paxille. No pedicellarize are present. 
The supero-marginal plates, forty-two to forty-four in number from the median interradial 
line to the extremity, are wholly visible when the starfish is viewed from above, They 
form a broad, sloping, or bevelled border to the abactinal surface, and even a portion of the 
infero-marginal plates is also visible; the latter forming exclusively the outline of the 
ray. The supero-marginal plates are rectangular, with the length greater than the height, 
excepting a few plates in the interbrachial arc, in which the dimensions are subequal. On 
the outer part of the ray the height is more than half the length. Each plate bears on its 
upper margin a short and comparatively delicate, straight, cylindrical, tapering, sharply 
pointed spine, the longest about 3°5 mm. in length, and they decrease very slightly as 
they proceed along the ray. The spines are directed upwards and at an angle of about 
45° towards the extremity. Rarely some plates bear two spines, one generally smaller 
than the other. The surface of the plate is covered with small, uniform, papilliform 
sranules, rather widely spaced on the middle of the plate, but becoming crowded and more 
elongate at the adoral and aboral margins. 
The infero-marginal plates correspond to the superior series, their line of union being 
perfectly horizontal. These plates have their surface curved, so that a portion is visible 
when the starfish is viewed from above, and they form entirely the outer margin of the 
ray. Indeed, beyond the middle of the ray their extent upon the abactinal area is nearly 
as great as on the actinal, and the rounding is slightly angular. Hach plate bears on the 
