98 THE ECHINODERMS OF TORRES STRAIT. 
Asterina nuda! sp. nov. 
(Plate 23, Figures 3 and 4.) 
R =18 mm.; r=11 mm.; R =1.64r; entire diameter, tip to tip of alternate rays, about 
33 mm. Disk thin, rather flat, but considerably arched in preservation; interbrachial ares 
quite distinct, but rays broad, flat, and rounded. Abactinal skeleton as usual in Asterina, 
of more or less imbricating plates, but these plates are nearly or quite naked; here and there, 
especially along the sides of the rays, one can detect with a lens lines or series of exceedingly 
minute short spinelets on the free inner margin of the plate, but these are insignificant; 
even on the plates of the disk margin the spinelets are very inconspicuous. Papule numer- 
ous but confined to the rays and the very center of the disk. Terminal plate of ray bare, 
more or less hemispherical, over 0.5 mm. in diameter. Madreporite triangular with rounded 
corners, about a millimeter along each side, situated less than 2 mm. from the center of the 
disk. No pedicellariz. 
Actinolateral plates in about 9 or 10 series at interradius, but in only about 6 or 7 
near middle of ray, well-defined and very regularly arranged. Each plate carries at its 
center, which is distinctly elevated, a linear series of 3 to 5 very slender delicate spinelets, 
more or less united by a very delicate membrane. The plates are otherwise smooth and 
bare. Adambulacral armature of 2 curved series, one on the furrow-margin, the other on 
the surface of the plate; marginal series of 7 or rarely 8 very slender spinelets, the middle 
ones longest, united by a delicate membrane; subambulacral series almost identical, but 
somewhat more curved. Oral plates large and conspicuous, keeled, smooth, and bare, 
save for the linear series of 5 or 6 slender spinelets, placed nearly parallel to the outer 
margin; marginal spinelets, slender, acicular, 8 to 10 on each plate, more or less membrane 
united, nearly or quite a millimeter long; innermost spine on each plate noticeably the 
largest, being stouter than the others, though not much longer. 
Color in life: upper surface deep pearl-gray, somewhat lighter in interradii and 
darkest on median part of rays; plates at tip of ray distinctly purple under a lens; marginal 
plates orange-brown; area around anus bright orange, madreporite white. Lower surface 
faintly mottled brown-orange and white; tube-feet whitish. Preserved specimen, dull 
brownish-yellow. 
Holotype, M. C. Z. No. 2299; under side of a rock fragment, shallow water, Weier, 
Murray Islands, Torres Strait, September 30, 1913. 
This seems to be a typical Asterina, yet quite distinct from any species hitherto 
described. While it agrees with leptalacantha in the nakedness of the upper surface, it 
differs in nearly every other character and is certainly not nearly allied to that species. 
It is equally distinct from the other Asterinas of Tropical Australia. 
ECHINASTERID£E. 
Echinaster luzonicus.? 
Othilia Luzonica Gray. 1840. Ann. Mag. Nat. Hist., 6, p. 282. 
Echinaster luzonicus Miiller and Troschel. 1842. Syst. Ast., p. 23. 
(Plate 10, Figures 2 to 4.) 
This is perhaps the most common sea-star of the Torres Strait region, for while it 
is not nearly so abundant at Mer as Linckia levigata, it is abundant at Thursday Island 
(along the north shore), where the blue Linckia does not occur at all. It was also found 
at Erub and at Badu. At Thursday Island nearly all the specimens were rusty-red, speckled 
? Nudus =naked, in reference to the smooth, bare condition of the abactinal surface. 
* See Fisher, 1919, pp. 426 to 435, for a most important discussion of Echinaster and Othilia and some of their 
component species. 
