THE STARFISHES OF THE HAWAIIAN ISLANDS. 
1099 
Supradorsal membrane thin but muscular; whole surface densely-beset with the tips of paxillai 
spinelets, which are very prominent though slender. Pedicels of paxillse are rather longer than the 
spinelets, of which there are about 10 widely radiating to each group. There are apparently no 
spicules present in the membrane, which is marked off by a meshwork of muscular bands into polygo- 
nal or roundish areas. In the type these bands are not at all conspicuous; in fact, are rather indistinct, 
but in a specimen from station 3472 they are very well marked. In this specimen each area is slightly 
sunken, and is further broken up by the protruding tips of paxillse spinelets, from which radiate 
numerous, much smaller, irregular fibers. On disk there are about a dozen large spiracula to each 
area, but on rays they are much less numerous. Oscular orifice large, but not conspicuous; surrounded 
by spines imbedded' in membrane. 
Ambulacral furrows narrow. Tube feet in 2 rows, with no tendency toward quadriserial arrange. 
. ment. Armature of adambulacral plates consists of a transverse series of 6 or 7 spines. The innermost 
spinule is short and slender, about one-half the length of the next, and is placed a little aborad to the 
remainder of comb, which thus appears to curve slightly at furrow end. Each succeeding spine is 
considerably longer than the last, the outermost being about one-half the length of adjacent actino- 
lateral spine, on the proximal portion of ray, but considerably more than one-half on distal portion. 
All radiate and are joined by a thin, semitransparent membrane, with shallow emarginations between 
the tips of the spines. The web, after passing the outermost spine, is joined to the actinolateral mem- 
brane (or the web of the actinolateral spines) somewhat aborad to that lateral spine corresponding to 
the plate. The adambulacral web of the first plate is confluent, just external to mouth plates, with 
web of first adambulacral of adjacent series. Segmental apertures are small. Aperture papillae small, 
“jawbone-shaped,” articulated by broader end, and free on aboral margin. 
Mouth plates, with a broad, free margin. Marginal spines 6 or 7, the innermost tapering, exceed- 
ing the interradial dimension of plate in length, and reaching beyond center of actinostome. The next 
spine is shorter and much slenderer, while the remainder of series rapidly decreases both in length 
and caliber. The first 4 spines free, but membrane tipped; fifth and sixth usually united by a web- 
Irregularity exists in that it is occasionally the second and third, or the third and fourth, which are 
united by membrane. On actinal surface is a robust spine, slightly longer and much stouter than the 
largest marginal, tapering and pointed, sheathed in membrane, free, and directed outward away from 
actinostome. In a smaller specimen this spine is relatively larger, club-shaped, transparent, pinkish 
in color and crystalline in luster. 
Actinolateral spines are very slender, rather long, the lateral fringe extending beyond the margin 
of test. Actinolateral membrane plane, wide. 
Color in alcohol, faded pinkish gray to yellowish gray. 
Localities: Type (no. 21184, U. S. National Museum) from station 3867, Pailolo Channel, between 
Maui and Molokai islands, 284-290 fathoms, fine sand and mud; bottom temperature, 43.8-44°; 2 
specimens. Taken also by the Albatross in 1891, 3472, south coast of Oahu, 295 fathoms, fine white 
sand; 3476, same locality, 298 fathoms, same bottom; 1 specimen each haul. 
This species is characterized by the reticulated supradorsal membrane, by the numerous, and 
prominent spinules of the abactinal paxillse, which give a very roughened appearance to the surface of 
the supradorsal membrane, and by the armature of the adambulacral plates and mouth plates. The 
spines of the mouth plates are not webbed, except 2 very small lateral marginals. The species appears 
to resemble most nearly Pteraster semireticulalus Sladen, from which it differs in the details of the 
adambulacral spinulation, the armature of the mouth plates, and to a less extent in the details of the 
dorsal surface. . 
Genus HYMENASTER Wyville Thomson. 
Hymenaster Wyville Thomson, The Depths of the Sea, London, 1873, p. 120. Type, Hym.ena.ster peliucidus Wyville Thomson. 
Hymenaster pentagonalis, new species. 
PI. XXXVIII, figs. 6, 6a-b; pi. XL, fig, 2; pi. xli, fig. 1. 
Marginal contour nearly pentagonal. No interbrachial arcs in perfect specimen, the sides being 
fairly straight. R=80 mm.; r=60 mm. R=1.33 r. Abactinal area nearly flat, or probably in life 
slightly convex when the tissues are fully expanded. Actinal area plane. Margin rather thick and 
fleshy, irregularly scalloped (probably due to unequal shrinkage). 
