Indo-Pacific Echinoderms — Clark 
257 
The outermost row extends to about the 
eighth inferomarginal, and the next disap- 
pears in the outer third of the ray. The plates 
of the oral surface are completely covered 
with densely crowded small spherical uniform 
granules resembling those on the aboral sur- 
face. The plates are only slightly elevated and 
are separated by shallow grooves. There ap- 
pear to be no papulae on the oral surface. 
There are no pedicellariae on either the oral 
or aboral surfaces. 
The furrow spines are flattened at right 
angles to the longitudinal axis of the ray and 
have broadly rounded tips. Of the two on 
each adambulacral plate, the adoral is slightly 
smaller than the aboral. Between the two 
spines on each plate there are two elongated 
grains, one above the other, 2 or 3 times as 
long as broad, the uppermost reaching to the 
upper third of the spines. These grains are 
visible only after dissection. On the mouth 
plates and on a few of the adambulacrals 
immediately following, grains (usually two) 
from the oral surface are intercalated between 
the spines. The outer portion of each adam- 
bulacral plate bears a rounded tubercle which 
is a little larger than the rounded end of the 
larger spine; this tubercle is separated from 
the furrow spines by usually two irregular 
rows of tubercles similar to those covering 
the oral surface. 
The color (dry) is buff white, with small 
irregular darker blotches. 
type: U.S.N.M., E.7999, from pool and 
pavement zone at the south end of Ngaru- 
maoa Island, Tuamotus; collected by Dr. 
Joseph P. E. Morrison, September 3, 1952. 
REMARKS: Ophidiaster perplexus falls within 
that section of the genus Ophidiaster which 
includes species with granules on the inner 
surface of the furrow between the furrow 
spines; with a single madreporite; with few 
papular pores in each papular area; and with 
few or no pedicellariae. This group includes 
only 0. pustulatus 2 indi 0. squameus, from which 
0. perplexus differs markedly in the arrange- 
ment of the plates on the aboral surface; in 
the fineness and uniformity of the granular 
covering; in the spherical form of the tuber- 
cles on the outer part of the adambulacral 
plates; and in having the granules on the 
furrow series double and between pairs of 
spines instead of between individual spines. 
In size and in general appearance Ophidiaster 
perplexus resembles Linckia multifora more 
closely than it does any other species of 
Ophidiaster, and it is possible that in the past 
it has been confused with it. The rays are 
slightly stouter than those of L. multi fora, 
and the plates on the aboral surface are larger, 
more tumid, and, at least on the bases of the 
rays and on the aboral surface of the disc, 
more regular in arrangement; the papular 
areas are much smaller, with fewer papulae. 
On the oral side the armature of the adam- 
bulacral plates is strikingly similar, but in L. 
multifora the grains on the inner face of the 
furrow are between the individual spines in- 
stead of between pairs of spines, as in 0. 
perplexus. In L. multifora there are two madre- 
porites which are much nearer the inter- 
brachial angles than they are to the center 
of the disc. 
Genus Linckia Nardo 
Linckia multifora (Lamarck) 
Asterias multifora Lamarck, Histoire naturelle 
des animaux sans vertebres, vol. 2, p. 565, 
1816 (?Seas of Europe). 
LOCALITIES: Marshall Islands, Eniwetok, 
Lt. William C. Harrington, July 9, 1944 (1 
specimen); Ujae Atoll, soft fine sandy tidal 
flat at the north end of Ujae Island, F. S. 
MacNeil, 1951-52 (3 specimens); Uterik 
Atoll, F. S. MacNeil, November 28, 1951 (3 
specimens); Wotho Atoll, Wotho Island, F. 
S. MacNeil (2 specimens). 
Gilbert Islands, Onotoa Atoll, G.O.C.-24 
(1 specimen); G.O.C.-36 (3 specimens and 
4 comets); G.O.C.-41 (1 specimen); Banner, 
B-8 (1 comet). 
Tuamotus, Morrison, 1884, 1886 (4 spec- 
mens); I860 (46 specimens) ; 1917 (2 comets); 
