1034 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Paxillse of abactinal area are large, roundish on disk, and very crowded; on rays arranged in 6 
regular longitudinal series at either side, becoming reduced to 5 on outer part of ray. In these regu- 
lar series the paxillse are very sharply quadrate, but over a fairly wide median radial area they are 
rounded in outline, considerably smaller than those of the regular series, are crowded, and have no 
definite arrangement. At base of ray paxillse of all 6 longitudinal rows bear a tapering, sharp, stout, 
often slightly curved spinule or thornlet, those on innermost series longest (2 to 4 mm.), thence 
decreasing in size toward margin, being usually quite short on outer 2 rows. On outermost of mar- 
ginal series (corresponding to the aborted superomarginal plates) there is now and then a central 
spinule as long as any of the innermost series. On outer part of ray beyond middle there are about 3 
definite longitudinal rows of spinules. The spinule is borne usually near inner edge of quadrate 
tabulum, or near the aboral inner corner, seldom in the center. Exposed surface of tabulum- is only 
slightly convex, and bears 20 to 25 stout, subclavate, papilliform spinelets, which become much 
heavier, rather flat-topped, and granuliform toward the center, where they often have the appearance 
of being bent the same way that the spinule is directed— -namely, diagonally toward inner aboral cor- 
ner of plate. Periphery of tabulum bears a series of numerous, blunt, much slenderer spinelets. 
Paxillse of median radial areas and disk lack enlarged spinule, are roundish, and smaller. The cen- 
tral group of spinelets is also more regular, increasing in size toward the center, where they are rather 
Luidia magnified.. Inferomarginal and adambulacral regular than the outer spines, the spines being much 
over surface of plate between the large spines. Here 
they are unequal in size, and irregular in distribution. In addition there is 1 (or rarely 2) 3-jawed 
are not to be confused with the larger ones, found in the interval between the adambulacral and inner- 
Arinature of adambulacral plates, which is borne on a transverse keel, consists of 3 spines, placed 
one behind the other, the median longest. Furrow spine flat, saber-like, and bluntly pointed. The 
next two are close together, and separated from furrow spine by an interval. They are long, straight, 
tapering, round tipped, and usually bent away from furrow. An inconspicuous, short, blunt, flat 
inferomarginal spines, is a row of 3 (occasionally 4, or at end of ray 2) large 3-jawed pedicellariae, 
which increase in size outward, the outermost being situated on a slightly greater prominence than 
the others. The innermost is situated just external to the outermost adambulacral spine, and reaches 
nearly halfway to top of this. Each pedicellaria is perched on the top of a discrete ossicle shaped 
very much like the shaft of a paxilla. The inner 2 ( b , c, see fig.) rest on the surface of the adambu- 
lacral plate, but the bottom of the outermost and largest is bent, and is wedged between the adambu- 
lacral and inferomarginal, representing the usual actinal intermediate plate, evidently. These ossicles 
are immersed in muscle, and are not readily comprehended unless treated with hot caustic potash. 
They represent really 3 longitudinal series of actinal intermediate plates, something very unusual for this 
flat-topped, clavate, and granuliform, resembling the 
large end of an apothecary’s pestle in miniature. 
Inferomarginal plates very numerous, short, and 
comparatively wide, each with a special ridge, sepa- 
rated from that adjacent by an unusually deep and 
wide fasciolar groove. Armature consists of a trans- 
verse, regular series of 5 or 6 spines, of which the outer 
2 or 3 are longer than the inner. The former are long, 
slender, tapering, very sharp, and slightly curved. 
Three is the most frequent number; the longest (7 to 
9 mm. ) is sometimes the outer ( when there are but 2 
enlarged lateral spines), sometimes the median, but 
there is little difference in the length of the three. 
The inner 2 or 3 of the group of 6 are often augmented 
by several auxiliary spinules. This group is less 
pedicellaria between the large lateral spines, making 2 or 3 for each plate. These pedicellariae, which 
most inferomarginal spines, are sessile, with a fairly broad base and blunt tip, being roughly conical. 
papilla is situated on adoral side of base of outermost spine. External to the latter, between it and 
