THE STARFISHES OF THE HAWAIIAN ISLANDS. 
1051 
Pentagonaster as here used includes the old species, P. pulchellus Gray, P. abnormale Gray, P bour- 
geti (Perrier), P. gunni Perrier, and P. dubeni Gray. It is thus employed exactly as emended by 
Verrill (1899, p. 157). The following species is nearer to the genus Tosia, apparently, than are any of 
the above-mentioned forms. 
Pentagonaster ammophilus, new species. 
PI. xvi, figs. 5, 5a; pi. xxn, figs. 1, 2. 
Pentagonal, flat, with nearly straight sides, or in some specimens faintly incurved; not produced 
into rays. R=24 mm. ; r=20 mm. R=1.2 r. 
Marginal plates are large, subquadrate, but wider than long, slightly convex, the upper and lower 
series corresponding except at corners of disk, where there are 2 inferomarginals to 1 superomarginal. 
There are in the type 6 upper and 8 lower plates on each side of the pentagon. The superomarginal 
plates form a broad, slightly raised bevel to margin of body, the edge of the pentagon being abruptly 
rounded. Four plates take up the greater part of each side, the plate nearest the ocular being small. 
Of these 4 plates the 2 median are smaller than either penultimate plate. The 2 distal plates at each 
angle are in contact medially. The distalmost plate varies much in size, sometimes being very small, 
and usually is of widely different size from the opposite companion. Terminal plate is small. 
General surface of superomarginals is beset with widely scattered, round, inconspicuous granules set 
in shallow pits, except in the outer (lateral) edge, which is covered with similar, larger, crowded 
granules. The line of demarcation between the 2 zones is abrupt but irregular, the crowded granules 
being confined to the vertical side of the disk. On inner margin there are usually 2 or 3 irregular 
longitudinal series of granules. Surrounding each plate there is, besides all of the above, a very 
distinct and regular series of bead-like granules. 
Inferomarginals are similar to superomarginals in shape, but form a slightly raised border without 
a bevel. They are similarly beset with granules, there being rather more along the inner and along 
the transverse margins. 
Abactinal surface is plane or very slightly convex. Plates are flat, closely set, regularly hexa- 
gonal, in 5 longitudinal rows along the radii, the median radial row easily distinguished and most 
regular. They are irregularly 5- or 6-sided, on interradii and center of disk, and much larger in latter 
area, the (apparent) basal and radial plates of the apical system being easily distinguishable. All 
abactinal plates are covered with close-set, bead-like granules, microscopically pitted or roughened. 
A peripheral series, more regular and often slightly elongated, especially on plates of radial areas, 
incloses a central group, which are either coordinated or else arranged in concentric rows. A typical 
plate from interradial area has 40 granules in the peripheral series, and 75 to 80 in the central group. 
The larger plates nearly double this number. On 3 or 4 of the regular plates in each radius, and 
usually on 1 or 2 in an interradius, set in a little pit, is a small 2-jawed, slender, subspatulate pedicel- 
laria. These jaws are ordinarily widely gaping, and rest in special depressions. Base of each jaw is 
much wider than the distal end. 
Adambulacral plates are about twice as wide as long, conspicuously smaller than actinal interme- 
diate plates, and form a very regular series on either side of the narrow furrow. Armature as follows: 
(1) A furrow series of 4 short, untapered spinelets, strongly compressed, edgewise to furrow. They 
have round tips and interlock with those of the opposite side of furrow. Either lateral spinelet is 
somewhat weaker than the 2 central members of the series. (2) On actinal surface 3 (sometimes 4) 
longitudinal series, each with 2 short, blunt, slightly flattened spinelets, which decrease in size as they 
recede from furrow. They are not very regularly arranged, and sometimes a fourth row of 2 or 3 
spinelets is added, especially along outer half of furrow. There are thus from 6 to 11 spinelets on the 
actinal surface of each plate — usually about 8. 
Actinal intermediate plates are large, mostly rhombic, arranged in fairly definite rows parallel to 
the furrow, the plates decreasing in size as they recede from furrow. They are covered with coarse, 
cylindrical, round-tipped granules, larger, longer, and less crowded than those of abactinal surface. 
The special pits of these pedicellarise are usually surrounded by 4 or 5 more pointed granules, a 
cleared space being present immediately around the group. 
Mouth plates are not raised above the general actinal surface. Companion plates aje closely 
united, their combined width equalling interradial dimension. Free margin of each plate straight, 
the combined plates forming a rather sharp angle. Furrow series of spinelets is 10, similar to but 
