1038 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Madreporic body is very small, situated halfway between center of disk and inner edge of supero- 
marginals; entirely hidden by paxillse. 
Color in alcohol, dull brown. 
Young: Two young, apparently of this species, were taken at station 4028. R=8.5mm.; r=5 mm. 
(smaller specimen)-. They differ much from the adult in general form, having short, stout rays. Each 
of the broad superomarginal plates (8 in number from median interradial line) has a naked area on the 
abactinal surface, similar to that of the adult except that in the young these extend around the 
interbrachial arc. Enlarged spinules of inferomarginals are present (absent on other specimen, how- 
ever) , but much reduced. Actinal intermediate plates are very few, and the actinal spinule of adam- 
bulacrals is not yet larger than the others. Furrow spinelets of adambulacrals 4 to 6. 
Locality: Type (no. 21158, U. S. National Museum) from station 3995, vicinity of Kauai, 427-678 
fathoms, fine gray sand and rocks; bottom temperature, 40.6°. Two young specimens were taken 
also at 4028, southwest coast of Kauai, 444-478 fathoms, on gray sand and globigerina. 
This species is distinguished by its short rays, broad marginal plates, very narrow abactinal 
paxillar area on rays, small actinal intermediate area, the plates of which are devoid of spines and 
of specialized fascioles between them, and by the enlarged spinule on the adambulacral plates. The 
madreporic body is entirely hidden. The species is thus very distinct from any Pacific form, and 
would seem to approach nearest to Ps. tessellatus Sladen from Cape of Good Hope, from which, how- 
ever, it is readily distinguishable by the shorter rays, broader marginal plates, with naked areas on 
superior series, by the hidden madreporic body, and by the absence of spinules from actinal interme- 
diate areas, where the granulation appears also much less compact. 
Pseudarchaster jordani, new species. 
PI. x, figs. 7, 7a; pi. xix, figs. 2, 2a. 
Rays 5. R=52 mm.; r=16.5 mm. R=3.15 r. Breadth of ray at base, between first and second 
superomarginals, 18 mm. 
Rays moderately long, robust, tapering continuously from a fairly wide base to a pointed extremity. 
Interbrachial arcs not so wide as in preceding species; rounded. Abactinal surface a trifle inflated 
over radial areas, and slightly sunken along interradial lines. 
Abactinal paxillar area is compact, not so narrow on rays as in preceding species. In the middle 
of R there are 5 longitudinal rows, the area here equalling in width one of the adjacent superomarginal 
plates. The paxillse are relatively larger than in Ps. myobrachius, and are arranged with beautiful 
regularity in a radial and numerous parallel series, the plates decreasing in size toward margin. They 
are also smaller in an apical area, inside the primary radials. A radial paxilla consists of about 10 to 
12 hexagonal or prismatic, granuliform spinelets placed on the convex summit of the pedicel, sur- 
rounded by a peripheral series of 15 to 18 smaller, unequal, slightly flattened ones which are consider- 
ably slenderer and do not form a regular series. The smaller paxillse differ only in having fewer 
spinelets. Papulae arranged in sixes about paxillse, lacking from* distal three-fifths of arm, as beyond 
eighth superomarginal. 
Superomarginal plates, 30 in number from median interradial line to extremity of ray, form a 
slightly arched bevel to margin of ray, but do not encroach so conspicuously upon the abactinal area 
as in the preceding species. They are uniformly covered with polygonal, flat-topped granules which 
increase in size toward the lower edge of plates. The thirteenth to twenty-third plates have a rudi- 
mentary bare spot near the abactinal end, but this appears to be lacking in a second specimen.^ 
Inferomarginals correspond plate for plate with superomarginals. On disk they encroach more 
upon the actinal area than do superomarginals upon abactinal. Excepting a regular peripheral series, 
the granulation is coarse and more irregular than that of superomarginals. The granules tend to 
become squamiform, and there is a very irregular transverse series of sharp, squamiform spinelets on 
each plate. These are more numerous in interbrachial arcs, and do not form a straight linear series. 
Adambulacral plates have an angular furrow margin. Armature as follows: (1) A palmate 
furrow series of 7 or 8 slightly curved, stout, round-tipped, compressed spinelets. The series is con- 
tinued along the aboral and adoral margins as 2 or 3 shorter, slenderer spinelets, the inner ones often 
standing on furrow margin in such a way as to form a portion of the palmate series. (2) On the 
general surface of plate, 2 (rarely 3, often only 1) lanceolate, slightly flattened sharp spinules similar 
to those of the actinal intermediate plates. Surrounding these are 6 or 7 blunt, papilliform spinelets, 
