THE STARFISHES OF THE HAWAIIAN ISLANDS. 
1017 
Genus TRITONASTER, new. 
Type Tritonaster craspedotus, new species. 
General form flat and depressed; disk of medium size; rays 5, moderately long, tapering gradually 
from a rather broad base to a pointed tip. 
Superomarginal plates much smaller than inferomarginals, especially on the outer part of ray; 
confined chiefly to abactinal surface; first 10 bearing weak spinules on the abactinal (=inner) edge. 
Inferomarginals very tumid, each bearing a transverse comb of 4 to 7 long, slightly curved seta-like 
spines, and, except in interbrachial arcs, defining ambitus. Fasciolar groove at bottom of each broad 
sulcus between 2 inferomarginal plates, or rather between the summits of their tumid portion, shallow, 
not specialized, packed with minute spinelets. Covering of marginal plates delicate papilliform spine- 
lets, giving a velvety texture. 
Abactinal integument thin, capable of being inflated; covered with small paxillae which are 
arranged in regular rows at sides of arms and disk. Those of the median radial portion of arms and 
center of disk without regular arrangement, and smaller and not uniform as to size. Bases of paxillae, 
or abactinal plates, are of different sizes, roundish, and spaced. Papular pores conspicuous, arranged 
irregularly about the plates, and in 2 series between the lateral abactinal rows of paxillae, to which 
region they are confined on the outer half of ray. Actinal interradial areas small, paved with small, 
roundish plates, a single series of which extends far along ray, but beyond the fourth inferomarginal 
these plates are only rudiments attached to edges of marginals. Actinal intermediate plates are 
covered with a compact group of delicate spinelets. 
Adambulacral plates are massive, with convex or angular margin to furrow. Armature consists 
of (1) a furrow series of a few stout spinelets flattened and blunt, and (2) on the actinal surface many 
slender spinelets arranged in 5 or more irregular, longitudinal rows. Usually about 6 of these spine- 
lets are grouped into a pedicellarian apparatus near the inner, aboral corner of the plate. Ambulacra! 
furrow wide, the tube-feet without suckers. 
Superambulacral plates present, slender, but well developed. 
•Mouth plates prominent, with about 3 series of actinal and 1 of marginal spines. Actinostome 
fairly large. 
Madreporic body moderately large, situated about its own diameter from the margin. Striations 
numerous, irregular, radiating from an eccentric point. 
This genus is characterized particularly by the structure and armature of the marginal plates. It 
is probably nearly related to Astropecten but differs from that genus in the peculiar, very tumid, infero- 
marginal plates and the reduced superomarginals, which, on the outer part of the ray, are almost 
abortive. The fascioles are much reduced in size and are quite unlike those of Astropecten. Indeed, 
the structure of the inferomarginals reminds one more of Persephonaster, to which the abactinal 
integument also is similar. Young of Tritonaster resembles Astropecten superficially, as might be 
expected, but the peculiar characters are greatly intensified in the adult. The presence of a series of 
rudimentary actinal intermediate plates, between the adambulacrals and inferomarginals (really 
attached to the actinal edge of the latter) , is, I believe, also a character of generic importance. 
Tritonaster craspedotus, new species. 
PI. v'm, fig. 4; pi. ix, figs. 1, la-k; pi. xi, fig. 1. 
Rays 5. R=61 mm; r=12 mm. R=5 r. Breadth of ray at base, between first and second 
superomarginals, 13.5 mm. 
Rays moderately long, flexible, fragile, tapering continually and gradually from base to a sharp 
point. Interbrachial arcs acute but rounded. Disk rather small. General form depressed and flat, 
the marginal plates forming a beveled edge to ray, except in interbrachial arcs, where the sides are 
perpendicular. Abactinal area subplane, thin, capable of being inflated or depressed. In some 
- specimens it is often so depressed that the inner ends of the ambulacral ridges form 5 humps on disk. 
Actinal area is plane. Ambulacral furrow takes up about a third the width of ray. Tube feet in 2 
rows, conical, without sucking disks. 
Abactinal paxillar area is not very uniform in character except at sides of area, where the paxillae 
are arranged in regular transverse rows and are uniform as to size; nor is the area at all compact. 
