54 THE ECHINODERMS OF TORRES STRAIT. 
ment. The whole abactinal surface is covered with rather coarse, spaced, rough granules, 
of diverse sizes, the largest at the summit of the conical plates, especially near the tip of the 
rays. Papular areas rather small with 3 to 10 papule; near the tip of the rays the papule 
are often single. Madreporite small, rounded, triangular, 1.5 mm. across, a little nearer 
center of disk than margin. Terminal plate small, covered with coarse granules, of which 
a few are conspicuously bigger than the others. 
Superomarginals 39, of which Nos. 5, 8, 14, 16, 18, 20, 22, 24, 26, 28, 30, and 32 are 
short and nearly flat, while the others, though of moderate size, are distinctly convex; 
all are covered with a coarse granulation, especially near center of plate and particularly 
near tip of ray; the largest superomarginals are not 2 mm. square. Inferomarginals 38, 
proximally smaller than those of the upper series, but becoming equal farther out on ray, 
only corresponding with them in position at irregular intervals; all are granulated like the 
superomarginals, but the dozen distalmost carry very coarse granules, of which 1, or often 2, 
become small tubercles. Actinolateral series well developed, reaching the twentieth infero- 
marginal or beyond; at base of ray there may be 2 actinolaterals to each inferomarginal, 
but for the most part there is only 1; the granulation of these plates is somewhat coarser 
than that of the lower marginals. There are small groups (2 to 5) of large papule between 
the two series of marginals and between the inferomarginal and actinolateral plates. 
Adambulacral plates rather large, averaging about 3 to each pair of inferomarginals; 
their armature consists of a furrow series of 4 subequal, flattened, but thick spinelets, with 
rounded and sometimes a little thickened tips; on a few of the proximal plates there is a 
fifth spinelet on the adoral corner of the plate, but this is noticeably shorter than the others; 
back of the furrow series is a second series of 3 (very rarely 4) shorter and thicker spinelets; 
the middle one of the 3 is usually the largest and may be conspicuously bigger than the 
others; on the outer margin of the plate are 2 or 3 smaller, more granule-like spinelets, 
of which 1 is often conspicuously larger than the others. Oral plates each with two series 
of spines, a marginal with 7 spines, of which the innermost is largest (nearly 2 mm. long) 
and a suboral with 5 spines of which the fourth, next to the outermost, is longest and 
stoutest. Color in life dull brown, quite dark, with all tubercles and the adambulacral arma- 
ture bright rose-red. Under a lens the epidermis appears very dark brown, the papule 
transparent gray, the granules on the tubercles rose-red, while those on the intertubercular 
spaces are dull yellowish or pale brown; the oral surface has a very slight orange tint; 
feet transparent white. Alcohol tends to bleach the specimens, and preserved material 
is light yellowish brown. 
Holotype, Museum of Comparative Zodlogy, No. 2325; southwestern reef-flat, Mer, 
Murray Islands, Torres Strait. 
This is the least common and the handsomest Nardoa occurring at the Murray Islands, 
its fine color making it instantly recognizable. Not only is the color distinctive, but the 
openly spaced granulation and the alternating arrangement of the superomarginal plates 
make the species easily recognized. Only 4 specimens were found altogether, and these 
occurred under coral slabs below low-water mark. The largest has R=78 mm., one ray 
has been broken (bitten?) off at the base, but has regenerated nearly 15 mm. Another 
specimen shows even more extensive injury; only one ray (R =63 mm.) is normal; two 
others, one on each side of the normal one, were broken (or from the appearance more 
probably bitten) off close to the disk but have begun to regenerate; the original fourth 
and fifth rays and more than half the disk are missing, but regeneration is well under way, 
the new rays showing ambulacral furrows over 2 mm. long. Even the holotype has one ray 
broken (pl. 29, fig. 1) about 15 mm. from the base, with a regenerated tip nearly 10 mm. 
long. These facts at least suggest that this species is peculiarly liable to injury, apparently 
from predatory fishes, and has its powers of regeneration correspondingly well developed. 
