1004 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
bb. Superomarginal series of spines rather delicate, continuous throughout ray; not absent from 
second or third plate. Lateral spines slender, 4 in an oblique comb ctenophorus 
aa. Superomarginals devoid of a series of erect spines; sometimes a single spine on first superomarginal. 
b. Size small; no leaf-like lateral spines. Actinal interradial areas small; superambulacral plates 
well developed. 
c. Size small; no leaf-like lateral spines. 
d. A single erect spine on first superomarginal plate; and a series of inconspicuous tubercles on 
plates of outer two-thirds of ray; the tubercles sometimes absent ..velitaris. 
dd. No spines whatever on superomarginal plates. Rays slender, flexible pusillulus 
cc. Size large; rays very long; a lateral series of large flat leaf-like spines. First 2 or 3 supero- 
marginals with a conspicuous, erect, spinule productus 
bb. Actinal interradial areas well-developed, paved with imbricating plates bearing spinelets in a 
paxilliform group; superambulacral plates present, but rudimentary in distal half of ray. 
No superomarginal spines , callistus 
Astropecten. polyacanthus Muller and Troscbel. 
PI. i, fig. 1; pi. ii, figs, 1, la, lb. 
Astropecten polyacanthus Muller and Troschel, System der Asteriden, 1842, p. 69, taf. v, fig. 3. 
Rays 5. R=47 mm. ; r=10.5 mm. R=4.3r. Breadth of ray at base, 12 mm. 
Arms rigid, very gently tapering to a bluntly pointed extremity. Sides of arms rather high, per- 
pendicular. Disk of medium size. Paxillar surface somewhat inflated. Interbrachial arcs acute but 
rounded. 
Abactinal paxillar area is rather compact, the paxillse being large and arranged in definite trans- 
verse rows, there being about 3 series to each superomarginal plate. Paxillse are largest in the inter- 
radial areas, midway between center and margin of disk, and also along median line of ray. Each 
paxilla consists of one or two central papilliform granules, surrounded by a radiating series of from 
5 to 8 slightly longer ones, the whole crowning a rather long pedicel. On disk the largest paxillse have 
upward to 5 central granules of unequal size, surrounded by 10-12 longer marginal ones, and occa- 
sionally one of the central granules is enlarged into a cylindrical pointed spinule. Less often one of 
the marginal spinelets is similarly enlarged (pi. ii, fig. la), but the two never occur on a single paxilla. 
Superomarginal plates, 22 in number from interradial line to extremity of ray, are much higher 
than broad and do not encroach conspicuously upon paxillar area. They form a rectangular edge to 
the abactinal surface, and the first plate is raised slightly above the level of the others. Except the 
second plate, and on one ray the third, each bears a perpendicular, stout, pointed, conical spine situ- 
ated on the abactinal face, slightly nearer aboral than adoral margin. The spine on first plate is 
longest and stoutest (as long as the longest spine of any inferomarginal, 4.5 mm.), the series decreasing 
in length toward tip of ray. The second superomarginal plate, which does not bear a spine, is smaller 
than either the first or third and is crowded by them. Plates are covered with small cylindrical papil- 
liform spinelets, which become stouter and squamiform toward base of spines. Wide fasciolar grooves 
between the plates (i. e., between the specialized, elevated, exposed surfaces). 
The inferomarginals, which are broader than high, correspond to superomarginals in number and 
do not extend beyond them laterally. Each plate bears a transverse series of 3 stout and relatively 
long, tapering, slightly flattened, sharp-pointed spines, the upper longest; to which is added a fourth 
spinule at inner end of series on third to seventh plates. First 2 plates usually have only 2 shorter, 
widely spaced spines. Plates are covered with slender papilliform spinelets in the fasciolar grooves 
and at upper end, these becoming longer, strongly flattened, and bluntly rounded or chisel-shaped at 
tip, in the vicinity of spines, and on actinal surface generally. 
Adambulacral armature is in 3 series. The furrow series consists of 3 long, stout spinelets, the 
median longest, blunt, somewhat triangular in cross section at its base, the lateral spinelets flattened 
and truncate. Second series consists of 2 stouter, much flattened, truncate spinelets, the one nearest 
aboral margin being the larger. Third series consists of 3 blunt, flattened spinelets somewhat smaller 
than the furrow series, the median being usually slightly the longest of the 3 and most flattened. 
There is an odd spine, smaller and pointed, situated behind the third series. In all there are usually 
9 spines on each adambulacral plate. 
