1012 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
each plate relatively more enlarged than in the adult. The lateral lamelliform spines are slightly nar- 
rower, and there are no enlarged spinelets between them and the superomarginal plates. In fact, the 
whole of the second series of inferomarginal spines is reduced in size and number. 
Localities: Type (no. 21145 U. S. National Museum) and 10 specimens from station 4102, Pailolo 
Channel, between Maui and Molokai islands, 122-132 fathoms, fine gray sand and foraminifera; bot- 
tom temperature, 59.7°. One immature specimen from same locality, station 4101, 143-122 fathoms, 
coral sand, shells, foraminifera. 
This remarkable and aberrant Astropecten is especially characterized by its large size, long, flat 
rays, very small disk, and regular longitudinal series of leaf-like marginal spines. _ It is quite 
different from any species heretofore described. Owing to the relatively small size of the disk, the 
species is very fragile at the junction of the arms and disk. Several specimens have a considerable 
portion of one or two of the arms regenerated. 
Astropecten callistus, new species. 
PI. VIII, fig. 3; pi. IX, figs. 4, 4a-4d; pi. XI, fig. 2. 
Rays 5. R=55 mm.; r=12.5 mm. R=4.4 r. Breadth of ray at base (between second and third 
superomarginal) , 1 2 mm. ; between fifteenth and sixteenth, 7 mm. 
Disk of medium size; rays long, rigid, tapering, narrow, sharp. Interbrachial arcs rounded. 
General form depressed. Actinal surface subplane, most prominent at mouth angles; abactinal surface 
subplane to very gently convex; capable of very slight inflation. The rays are characterized by 
subvertical sides, and they taper most in the basal third, and only very slightly in the outer half, 
giving a peculiarly attenuate appearance. The terminal plate is large, subcylindrical, and the tip of 
ray is usually bent upward. 
Abactinal paxillar area is compact and well defined to tip of ray, decreasing in width in proportion 
to ray. Paxilhe are large and close set, largest in interradial areas and at base of ray, conspicuously 
decreasing in size toward the center of disk, and much more gradually toward tip of arms. Each 
paxilla consists of a rather low, cylindrical pedicel, nearly flat-topped, surmounted by a central group 
of spaced granules, stout, round-tipped, and varying in number from 3' to 8, or even 10. The central 
3 or 4 are largest. This group is surrounded by a peripheral radiating series of 18 to 20 smaller, 
slender, clavate spinelets or elongated granules, the whole very regular and elegant in appearance, 
and much resembling a composite flower. In the largest specimen (R=64 mm.) there are as many as 
24 spinelets in the marginal series, and 12 to 15 in the central group. On disk the pedicels are some- 
times elliptical in section, and usually so on the radial portions of the rays. The pedicels are expanded 
into a fairly large, stellate base. These plates, which are close together and which are joined by their 
lobes, are generally circular or subhexagonal in contour, the processes, about 6 in number, being short, 
abrupt, and round-tipped. The latter impinge upon neighboring plates, the papulae passing through 
the interspaces between them. The papulae are single, and are disposed generally over the abactinal 
surface. 
Superomarginal plates, about 40 in number from the median interradial line to tip of ray, are 
rectangular, about as high as broad, except in interbrachial arc, where the plates are confined almost 
entirely to the side of ray, to which they form a uniformly arched margin. The exposed surface of 
the plate is very slightly convex along its transverse axis, and with regard to the longitudinal axis the 
plates form a very even arc. They are devoid of spines, and are covered with rounded, subconical 
granules, largest at upper end of plate, becoming papilliform in grooves between the exposed surfaces 
and at lower end. In the largest specimen 1 or 2 of these granules are enlarged on the marginal angle 
of ray, but they are quite inconspicuous. 
The exposed surface of each inferomarginal, like that of superomarginals, is separated from its 
neighbors by a fasciolar groove, and there is also a conspicuous groove between, the upper and lower 
series, seen when the ray is viewed from the side. On outer third of ray the 2 series of marginal 
plates do not always exactly correspond, but there is considerable variation in this respect. Infero- 
marginals encroach scarcely more on the actinal surface than do superomarginals on the abactinal, 
except in interbrachial arc. They form an arched bevel to the margin of actinal area, and in some 
specimens extend just a trifle laterally beyond superomarginals. Each plate bears a row of 3, often 4, 
short, flattened, tapering, pointed spines, disposed along the median transverse line of the plate. 
