1102 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Actinolateral spines rather widely spaced, the fifth or sixth from the mouth plates being longest. 
They extend beyond edge of body, and there are 18 to each side of a ray. Actinolateral membrane 
transparent, finely and irregularly marked by fibers, much after the manner of the supradorsal mem- 
brane. There is a lateral fringe, which extends a short distance beyond the margin of the body. 
Color in alcohol, translucent yellowish gray. 
Locality: Station 3824, south coast of Molokai Island, 222-498 fathoms, coral, broken shells; 
bottom temperature, 49.5°; 1 specimen, type no. 21186,' U. S. National Museum. 
Benthaster is an exceedingly rare type, the other 2 species having been dredged by the Challenger. 
Benthaster wyville-thomsoni was taken in 2,900 fathoms in the mid-north Pacific, between Yokohama 
and San Francisco, near the meridian 170° E., from red clay. B. penicillatus came from off the north 
coast of New Guinea, southwest of the Admiralty Islands, 1,070 fathoms, blue mud. It is somewhat 
remarkable, therefore, that the present form should have come from not nearly so great a depth. 
Benthaster eritimus differs in several respects from the 2 other members of the genus. In the first 
place the nidamental cavity is more spacious, and better developed, as the pedicels of the dorsal 
paxillse are rather long, and thus support the- supradorsal membrane well above the true abactinal 
wall of the body. The membrane appears to be plentifully supplied with muscle fibers, which form 
a sort of reticulum, although they are rather simple in structure. Spiracula are present, especially 
over the region of the bilobate or trilobate, fleshy “papulae ”. These spiracula are said to be absent 
in the 2 other species. The spinelets of paxillse are rather fewer in number. Adambulacral armature 
consists of 5 furrow spines and an aperture papilla. Lateral fringe is present. Marginal plates are 
much reduced and are confined to the extreme tip of the ray. 
Order FORCIPULATA Perrier. 
Family ZOROASTERIDiE Sladen, 1889. 
Zoroasteridse Sladen, Report on the Asteroidea collected during the Voyage of H. M. S. Challenger , etc., Zool., vol. xxx, 
1889, p. 416. 
Genus ZOROASTER Wyville Thomson. 
Zoroaster Wyville Thomson, The Depths of the Sea, 1873, p. 154. Type Zoroaster fulgens Thomson. 
Zoroaster spinulosus, new species. 
PI. XXIV, fig. 3; pi. XLI, fig. 2; pi. XLII, figs. 5, 6. 
Rays 5. R=118mm.; r=ll mm. R=10.7r. Breadth of ray at base, 12 mm. R=10.6r to 14.3 r. 
Rays very long and slender, subcylindrical, tapering gradually to a prolonged, finely pointed 
extremity. Abactinal surface arched, with very evident lateral faces to rays. Edges of furrow tumid. 
Disk small, slightly tumid, center rather higher than the median ridge of rays. Interbrachial angles 
extremely acute. 
The calcareous skeleton of whole test is composed of roughly diamond-shaped or slightly lobed 
hexagonal plates, all with rounded corners, arranged in perfectly regular longitudinal and transverse 
rows. Median radial series is composed of the largest plates of ray, while those of the disk are largest 
of all. Their arrangement (which is to be regarded as of generic rather than specific importance) is as 
follows: Surrounding a scalloped, dorsocentral plate are 5 radially situated infrabasals of about the 
same size. An odd plate may be present between 1 or 2 pairs of these. Outside of infrabasals are the 
interradially placed, much larger, oblong basals, one of which has the madreporic body at its outer 
edge. Outside of and alternating with these are 5 primary radials about the same size as the basals. 
Proceeding outward from each primary radial, along the median line of ray, is a regular longitudinal 
series of plates, tumid or tuberculated, hexagonal in general form, but with each edge of the hexagon, 
especially that on either side, indented, giving a shield-shaped appearance. On each side of the radial 
series is a parallel adradial row of smaller plates which is succeeded by another parallel, somewhat 
larger series of plates, slightly tumid, and forming a faint ridge at junction of lateral and abactinal 
faces of ray. The edges of these plates and those of the radial series overlie the adradials. Between 
this marginal series and the adambulacral plates are 5 additional, perfectly regular, longitudinal series, 
the plates of which likewise form regular transverse series with the marginals, there being thus 6 plates 
to each transverse series beyond the adradials. The lower end of the plates of each lateral series, 
