THE STARFISHES OF THE HAWAIIAN ISLANDS. 
1025 
outer edge of the peristomial membrane. The teeth are consequently a part of the superficial, not of 
the marginal series. This arrangement bears a striking resemblance to that found in Psilaster gracilis 
Sladen, but in other respects the two species are dissimilar. 
Actinal intermediate plates are confined to a small area in the interradial region, and extend 
along the ray as far as the seventh inferomarginal plate. They are arranged in regular series extending 
parallel with the interradial line from the inferomarginals to the adambulacrals. Opposite first 
inferomarginal there are 3 series, abutting against mouth plate and first three adambulacrals; between 
first and second inferomarginals, 1 series, meeting fourth adambulacral; opposite second inferomar- 
ginal, 1 series of 3 plates meeting fifth adambulacral; third inferomarginal, 2 series of 3 and 2 plates 
meeting sixth and seventh adambulacrals; fourth inferomarginal to seventh, a single longitudinal 
series of plates, the last 2 being rudiments. Actinal intermediate plates are armed with groups of 
spinelets shorter but otherwise similar to those of the actinal surface of adjacent adambulacrals. 
Plates frequently bear a spinule in the center, flattened, sharp, and tapering, which resembles those 
of the ventral series of the proximal inferomarginal plates. In one specimen these are entirely absent, 
and the spinelets here tend to group themselves into a pedicellarian apparatus. This is true also of 
many of the actinal intermediate plates of typical specimens. 
Madreporic body small, partially obscured by neighboring paxillse; coarsely striated. It is 
situated about 3 times its own diameter from the inner border of the superomarginals, and nearly 
bisects the minor radius. 
Color in life: Abactinal paxillar area light dirty green; rest of arms light flesh pink; tube feet 
raw sienna. Color in alcohol, bleached yellowish or dirty white, brownish on paxillar area. 
Young: In an immature specimen in which R = 21 mm. and r = 6 mm., the superomarginal plates 
are 13 in number and very massive, almost obliterating the paxillar area of the distal two-thirds of 
ray. Paxillse have less numerous spinelets than in the adult, there being about 8 to 10 altogether. 
Spines of inferomarginal plates of normal number, but shorter than in the adult. Terminal plate 
with 3 blunt papillae. Adambulacral spinelets of marginal series 8 or 9, the new spinelets being added 
at sides; spinelets of actinal surface in 2 rows. Actinal intermediate plates are fewer in number than 
in adult, the new plates being added next to inferomarginals and growing along ray, extending in this 
specimen only as far as fifth adambulacral. Mouth plates similar to adult, but with fewer spinelets, 
the teeth being very prominent. Membranous investment of all spinelets relatively thicker than in 
adult. Another example (R = 48 mm. , r = 9 mm. ) is intermediate between the above and adult in 
nearly all respects except proportions. 
Variations: A specimen from station 3887 has rather broader rays than other examples, and the 
superomarginal plates encroach a trifle less upon the abactinal paxillar area. In another example, 
from station 4028, the spinules on the actinal intermediate plates are more frequent and longer than 
in the type. The spines of the inferomarginals are likewise more prominent, there being an additional 
spine throughout in the superior series; the inferior series extends farther along ray than in normal 
specimens, and its spinules are more prominent, forming a continuous series with the dorsally placed 
ones. Still another specimen (station 3995) lacks entirely the usual spines of the actinal intermediate 
plates, and the spinelets of these plates and of the actinal surface of the adambulacrals are relatively 
about half as long as those of the type, there being more plates which possess the specially grouped 
papillae acting as pedicellarise. In choosing the type I selected a form which is most representative of 
the entire series in the totality of its characters. 
Measurements of adult specimens of Psilasteropsis cingulata, in millimeters. 
Major radius 
' 95 
78 | 
80 
77 
88 
81 
93 
90 
Minor radius 
18 
15 j 
16 
15 
17 
17 
18 
21 
Width of ray between second and third 
superomarginal plates 
18 
17 
17.5 
15.5 
17.6 
16.5 
19 
20 
Breadth of paxillar area, same place 
12 
ii ! 
10 
12 
10 
13.5 
16 
Number of superomarginal plates 
33 
30 ; 
32 
33 
33 
31 
35 
30 
Localities: Type (no. 21150, U. S. National Museum) from station 3997, off Ukula Point, Kauai 
Island, 418-429 fathoms, fine gray sand, brown mud; bottom temperature 41°. Taken also at the 
following stations, 11 specimens in all. 
