EASTERN TROPICAL PACIFIC ASTEROIDEA. 93 
oral surface being quite unusual. The very high and steep jaws are no less 
remarkable, so that entirely apart from the peculiar shape the species will be 
easily recognized when next it is taken. 
Hymenaster trias,! sp. nov. 
Plate 3, fig. 1, 2. 
Rays 5. R=40 mm.; r= 28 mm.; R= 1.43 r. Body highly arched, 
the vertical diameter at center being about 20 mm. but this may be due in part 
to marginal contraction. Form distinctly stellate, the interbrachial arcs being 
rather deep and angular. Rays quite acuminate, the free narrow tip, about 
8 mm. long, being turned up against the aboral surface of the ray. Paxillae 
covering the whole dorsal surface, the interbrachial areas, as seen from above, 
practically wanting. Paxillar spinelets five to eight usually six, longer than 
stalk, very slender and projecting through the thin supradorsal membrane for 
nearly or quite half their length. Spiracula fairly numerous, quite large, irregu- 
larly scattered. Osculum large, about 10 mm. across; each valve with twelve 
to fourteen spines of which the outermost are shortest but are about three fourths 
or at least two thirds as long as the middle ones. Actinolateral spines few and 
widely spaced; there are about sixteen of which the fifth is longest. The mem- 
brane in which they lie is thin and transparent. Adambulacral armature con- 
sists of two well-spaced, subequal, slender, brittle spines, 4-5 mm. long; the tip 
is blunt and the spines are not at all sacculate. Aperture papilla distinctly 
stalked, the blade about as wide as high, except that the upper margin has more 
or less of a membranous extension, which is, however, never very great. Oral 
plates united to form a very wide jaw, the width being considerably more than 
twice the length; the median keel is quite conspicuous but slopes gradually to 
the inner tip which is wide and rounded; each plate carries three oral spines, of 
which the innermost is as long as the jaw, or longer, and stands a trifle back 
from the margin and the outermost is about two thirds as long and stands on 
the margin near the outer proximal corner of the plate; the middle spine is 
intermediate in size and position. There is no suboral spine. None of the 
spines are sacculate. Color, both above and below,:pale yellowish. 
Station 4672. Peru: southwest of Palominos Light House, 88 miles, 2,845 fms. Bott. temp. 35.2°. 
Fne. dk. br. infus. m. 
One specimen. 
1 rp.as = three, in reference to the armature of the oral plates. 
