1098 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
stand just external. Armature, therefore, consists of 7 (becoming 6 at about middle of ray) long, 
slender spinules, united by a delicate web, forming a slightly curved, transverse, oblique series, placed 
on a tumid ridge on the rounded furrow margin, trending from the aboral furrow side outward and 
adorad. Inasmuch as the plates are set obliquely the series is not far off the transverse axis. This 
series is immediately continued on the aboral process of the adjacent adoral plate in 2 or 3 long slender 
spinules, also placed obliquely. The spines of the two series are united from base to tip by a single, 
continuous, delicate web. On the proximal portion of rays (the distal part being too injured to verify 
the structure there) the outer groups of spines of successive plates are united by a delicate longitudinal 
membrane, as shown in the figure (pi. xl, fig. 3a). This membrane is perforated between successive 
transverse series, and extends across interbrachial area just behind mouth plates, there being also a 
perforation at the outer end of combined dentary plates. The spines of inner or marginal series 
decrease in size toward aboral end of series, the lagt or inner spiiielet being short (1 to 1.5 mm. ). The 
longest spines are about 5 or 6 mm. in length. Outer series is subequal or slightly longer than longest 
inner spines. 
Mouth plates prominent actinally, and triangular in shape, something like a plowshare. Each 
rises toward a perfectly straight, median suture to form a prominent keel. Edge of plate toward 
actinostome is broad, faintly convex, and produced just a trifle at the median suture. The outer end 
of the combined pair is also prolonged, so that it overhangs interbrachial area. Margin adjacent to 
furrow -very short, concave, and high in furrow. Distal (adambulacral) margin concave, the suture 
slightly raised, so that a broad furrow is present between the first adambulacral and the smooth actinal 
face of plate. Armature consists of a series of 6 spines and spinelets on margin toward actinostome. 
The inner 3 or 4 are rather long, reaching nearly to outer end of plate, and are united by a web. The 
outer 2 or 3 are very short. On the short margin adjacent to furrow, near the shorter marginal spine- 
lets, are 2 upright spinelets about the same length as the latter. The general surface of the plates is 
quite smooth, and the spines, as well as those of the adambulacral plates, are similar in structure to 
the abactinal spines already described, although much larger and stouter. They are nevertheless 
very delicate, and break almost at a touch. 
Madreporic body large, convex, subcircular, very fragile, situated rather nearer center of disk than 
midway to margin. Striations are obscure and very irregular. Ambulacral plates are large, with 
very broad ends, the upper ends especially flaring. The apertures between the plates are large. 
Color in life, dull pinkish ( “ salmon pink ” ). 
Locality: Station 4157, vicinity Bird Island, 762-1,000 fathoms, white mud, foraminifera, rocks; 
bottom temperature 38°. Type no. 21183, U. S. National Museum. 
Family PTERASTERID 7 E Perrier, 1875. 
Pterasteridse Perrier, Revision de la Collection de Stelliirides du Museum d’Histoire Naturelle de Paris, 1875, p. 381. 
Key to Hawaiian genera of Pterasteridx. 
a. Armature of adambulacral plates forming transverse combs, the spines being united by a web. 
Actinolateral spines forming a free, independent lateral fringe; not merged in the actinal floor; 
supradorsal membrane with muscular fibrous bands Pterarter 
aa. Armature of adambulacral plates not forming transverse combs. Spines independent, not united 
by a web. 
6. Nidamental cavity spacious. Supradorsal membrane well developed; spinelets of paxillse not 
protruding through, but supporting the membrane Hymen-aster 
66. Nidamental cavity small; supradorsal membrane exceedingly thin; muscle fibers absent or rudi- 
mentary. Spinelets of paxillae fascicular, protruding a great portion of their length naked 
through the membrane. Size small Benthaster 
Genus PTERASTER Muller and Troschel. 
Pteraster Muller and Troschel, System der Asteriden, 1812, p. 128. Type, Asterias militaris O. F. Muller. 
Pteraster reticulatus, new species. 
PI. xxxviii, figs. 5, 5a; pi. xxxix, figs. 1, 2. 
Marginal contour stellate. Interbrachial arcs angular. R=39 mm.; r=23 mm. R=1.7 r. 
Breadth of ray at base about equal to r. Disk not high. Abactinal surface rounded, sloping gradually 
to tip of ray. Sides of rays straight. Actinal surface sunken toward actinostome. 
