REPORT ON THE ASTEROIDEA. 39 
defined longitudinal lines may be distinguished ; their presence amongst the small and 
comparatively inconspicuous general paxille of the abactinal surface forms a striking 
feature in the species. 
The supero-marginal plates, thirty-eight in number from the interradial line to the 
extremity, form a well-defined though rather narrow border to the rays. The breadth, 
height, and length are about subequal, the last dimension being slightly in excess, and the 
plates are slightly convex and subtubercular abactinally. Hach plate bears a robust, conical, 
tapering spine, about 4 mm. in length midway along the ray, directed perpendicularly to the 
abactinal plane of the ray. These spines diminish a trifle in length as they approach the 
base of the ray, but increase in robustness; whilst they decrease both in length and 
robustness on the outer part of the ray. On the outer side of this spine is usually a smaller 
and more delicate spinelet directed outward at an angle of about 45°, and occasionally 
two may be present, and sometimes they are little more than elongate miliary spinelets. 
The rest of the plate is covered with numerous very short, delicate, pointed miliary 
thornlets. 
The infero-marginal plates alternate with the superior series, and their dimensions are 
subequal. Each plate bears three robust, conical, tapering, pointed spines, similar to those 
on the supero-marginal plates. These spines form a series along the median transverse 
line of the plate; the outermost or lateral spine is the longest, and slightly greater than 
the supero-marginal spine ; the innermost spine of the three is the smallest, and is about 
half the length of the lateral one. The longest lateral spine is the third or fourth 
from the interradial line, and measures about 5 mm., and the succeeding ones decrease 
slightly in length as they proceed outward. The rest of the plate bears a few widely 
spaced, small, miliary thornlets, some of which at the base of the large spines are more 
elongate than the others. There is a naked suture-line between each plate. 
The adambulacral plates are slightly longer than broad, and with only a slightly convex 
margin towards the furrow. Their armature consists of :—(1.) A furrow series of six short, 
rather thick, cylindrical, obtusely pointed spinelets, the inner pair slightly longer, and 
the outer one at each extremity very much smaller, than the rest; their posture resembles 
that of the fingers of a hand held slightly concave. (2.) On the actinal surface of the 
plate are two robust, slightly tapering but obtusely pointed spinelets, one behind the other 
in the transverse median line. The innermost stands close behind the marginal series, the 
outermost is slightly larger and is subequal in size to the innermost of the three spines on 
the infero-marginal plate. Two or three minute miliary spinelets may be present on the 
outer margin of the plate, but the rest of the plate has a naked appearance, and is only 
covered with membrane. 
The mouth-plates are powerful and slightly convex; each plate of the united pair 
bears on its free margin six mouth-spines, the innermost being the longest, most robust, 
and slightly compressed ; the others decrease as they recede from the mouth and become 
