REPORT ON THE ASTEROIDEA. 631 
tube-feet.. It would seem probable that the function of the numerous pedicellariz on the 
sacculi of these spinelets was mainly, if not wholly, that of keeping the tube-feet clean. 
The actinal spinelet is about 5 mm. in length at 60 mm. from the disk, and is articulated 
on a robust tubercle, which occupies most of the actinal surface of the plate between the 
middle and the adoral end. It is encased in a delicate membranous sheath, crowded with 
very small pedicellarize. The lateral spines are not remarkable for their length, being 
about 9 to 10 mm. at 70 to 80 mm. from the disk; they are articulated on a tubercle-like 
rudimentary infero-marginal plate ankylosed on the lateral margin of the adambulacral 
plate, in a line with the tubercle on the actinal surface, and are rather robust at the 
base, but taper to a fine extremity, and they are encased in a delicate membranous sheath 
crowded with small pedicellariz. 
The actinostome is of great width, its diameter being 13 mm. in a disk measuring 23 
mm. The buccal membrane is thick and opaque, and the margin of the mouth is beset 
with a closely crowded villous fimbriation (? probably an exposure of the internal surface). 
The mouth-plates are small and inconspicuous, somewhat in the form of a.truncate wedge, 
the adoral margin of the pair presenting only a slightly convex margin. Lach plate bears 
two small mouth-spines about 1 mm. in length; the inner pair are a little removed from 
the median line of juncture, and are directed horizontally over the buccal membrane, 
usually parallel to one another, or only slightly divergent; the second pair are at the 
extreme edge of the adoral margin of the plates, 7.e., one spine on each plate, and are 
directed horizontally at a right angle to the median interradial line, and in such a manner 
that with the corresponding spine of the neighbouring mouth-angle a bar is formed across 
the ambulacral furrow at the margin of the actinostome. Both the mouth-spines are 
encased in a delicate membranous sheath, that of the inner pair being wide and bag-like, 
usually expanded at the tip and pyriform, and numerous small pedicellarie are borne 
upon the membrane. The outer pair of spinelets which cross the furrow have the appear- 
ance of being imbedded in the actinostomial membrane, and their presence is only detected 
by the pedicellariz. A robust secondary mouth-spine is placed well back on the actinal 
surface of each plate, articulated on a tubercular eminence, and encased in a rather wide, 
delicate, membranous sheath crowded with pedicellariz. 
The madreporiform body is small, about 2°5 mm. in diameter, convex, subtubercular, 
and situated quite at the margin of the abactinal surface of the disk, at the summit of one 
of the cleft-like interbrachial arcs, its position in relation to the plane of the abactinal 
surface being slightly oblique. Its surface is marked with a few highly convoluted 
striation-furrows, and the margin is surrounded by an indistinct circlet of the abactinal 
tegumentary spinelets. A very distinct anal aperture is present ; it is excentric in position, 
and the margin is surrounded with rather larger spinelets than elsewhere upon the disk, and 
a retracted tubular structure with punctured extremity may be seen within its periphery. 
Colour in alcohol, a bleached yellowish white. 
