1026 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Reeord of localities. 
Station. 
Locality. 
Depth. 
Nature of bottom. 
3824 
3887 
3995 
South coast of Molokai Island 
North coast of Molokai Island 
Vicinity of Kauai Island 
do 
Fathoms. 
222-498 
552-809 
427-696 
444-478 
352-357 
Coral rock, broken shells. 
Globigerina mud. 
Fine gray sand, rocks. 
Gray sand, globigerina. 
Fine gray sand and mud. 
4028 
4123 
Southwest coast of Oahu Island 
This species is most nearly related to Psilasteropsis patagiata (Sladen) from off the Cape Verde 
Islands, from which it may be distinguished by the following characters: The relatively longer and 
slenderer arms; more strongly tumid marginal plates; absence of incipient pedicellarise on superomar- 
ginals; larger paxillse, with more numerous spinelets; relatively narrower paxillar area; details of 
spinulation of inferomarginals; by the adambulacral armature; armature of the mouth plates, the last 
character showing a resemblance to mouth plates of Psilaster gracilis, which, also, is not a typical 
Psilasler. 
Genus DIPSACASTER Alcock. 
Dipsacaster Alcock, Ann. N. H., ser. 6, vol. XI, 1893, p. 87. J. Asiat. Soc. Bengal, vol. lxii, 1893, p. 172 (no diagnosis). Type 
D ipsacaster sladeni Alcock. 
Dipsacaster nesiotes new species. 
PI. ix, figs. 3, 3a; pi. x, figs. 2,.2a-t>; pi. xii, figs. 1, 2. 
Eays 5. R=89 mm., r=27 mm. R=3.3 r. Breadth of ray at base, between first and second 
superomarginals, 30 mm. ; between fifth and sixth 25 mm. (See under variations. ) 
General form flat, depressed; rays tapering arcuately from a broad base to a bluntly pointed 
extremity. Disk large. Interbrachial arcs wide, well rounded, involving the first few marginal 
plates. Actinal area subplane. Abactinal area capable of considerable inflation, the paxillar area of 
rays often arched in such a way as materially to lessen the width of arm. Disk usually more or less 
inflated, but the integument is quite flexible, and no 2 specimens are alike in this respect. When the 
abactinal paxillar area is considerably inflated, the animal has a less flattened appearance and the 
rays appear quite narrow. 
Abactinal paxillar area fairly compact, covered with paxillse arranged on either side of the median 
radial line in regular obliquely transverse series. These series assume an interradial direction on the 
disk. On the center of disk and along median radial line no regular arrangement is apparent. 
Paxillse are rather large, with a prominent pedicel which is expanded into an irregularly circular or 
elongated base, and a subglobose crown covered with a compact coordinated group of very many small, 
delicate, cylindrical, bluntly-pointed, almost capillary spinelets. An average paxilla on a ray would 
have 30 to 40 of these spinelets, and the larger ones on the disk from 50 to 100. One of the largest 
paxillse on the madreporic body has 150. The spinelets are so compactly placed that it is almost 
impossible to count them accurately. Papular pores are generally distributed and are largest on the 
lateral portions of the abactinal area; papulse single. Anal opening conspicuous, surrounded by a 
membranous periproct. It is situated about 5 mm. from the center of disk. (See p. 1028, Anatomical 
notes. ) 
The marginal plates form an angular edge to ray, the inferior series extending laterally beyond 
the superior and defining the margin of ray. Superomarginal plates are oblong to subquadrate, are 
slightly arched, and form a conspicuous border to the abactinal area, to which surface they are wholly 
confined on the ray. In interbrachial arc the plates are oblong, shorter than wide, and their exposed 
surface stands at an angle of about 45° with the horizontal. On the ray they form a low, slightly 
arched bevel, and at first glance appear to lie in an almost horizontal plane. Their entire width can 
be seen when the animal is viewed from above. Superomarginals do not exactly correspond to 
inferomarginals on outer half of ray, so that the suture between the 2 series follows a zigzag course. 
Sometimes for a short distance the inferomarginals exactly alternate with the superomarginals. But 
the number of plates in the 2 series is the same (in type 33). Superomarginals uniformly covered 
with minute pointed spinelets. In one specimen about 4 enlarged granules, with several of inter- 
