1018 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Along median radial area of ray and central portion of disk, paxillse are not regularly arranged nor 1 1 
considerable flexibility to the dorsal integument. The paxillse of the regular series are rather close j 
together but the rows themselves are separated by nearly twice the diameter of a paxilla. The j 
paxillse consist of a short pedicel or tabulum surmounted by from 4 to 20 very delicate, subequal , 
spinelets, either coordinated into a compact group, or with outer spinelets diverging. Scattered in > 
a.mnnff the larger naxillse are manv small, intermediate ones, with from 4 to 10 nsnnllv eoorflinafefl 
smaller than inferomarginals, except the first 4 or 5 in interbrachial arc, which are only slightly 
the latter with their armature of long delicate spines forming the border of ray. In interbrachial arc 
the height (or width) of superomarginals equals length, and by the ninth plate the width has so j 
decreased that it equals only one-half the length. The plates further decrease to mere bands, or ossicles 
placed end to end, forming an inconspicuous border to the paxillar area (pi. ix, figs. 1 h-j) . All are 
somewhat tumid. Margin of plate toward paxillar area is slightly convex, and owing to tumidity is 
raised slightly above the level of the area. Plates are covered with tiny, uniform, very delicate, close- : 
set, papilliform spinelets, giving a velvety texture to the surface. Each spinelet is slightly clavate, 
blunt. Membranous investment is invisible. The first 10 superomaTginals each bear a delicate, j 
tapering, sharp spinule on the inner margin, placed rather nearer the aboral than adoral end; those of j 
first 2 plates short, becoming longer on following 4 or 5, then short again. All are very fragile and 
none are as long as their respective plates. 
Inferomarginals correspond to superomarginals in number, and encroach upon actinal surface I 
more than do the superomarginals upon abactinal. Actinal margin of plate is convex, abutting against ; 
adambulacrals throughout the greater part of the ray, as the actinal intermediate plates are quite 
inconspicuous. Plates are set obliquely tb long axis of ray; very tumid, the lateral portion being 
raised into a conspicuous boss, so that when viewed from either above or below the margin of ray appears 
to be deeply scalloped, the summit of the bosses being fairly acute, the sulcuses between angular. Each 
boss is surmounted by a comb of remarkably long, slender, delicate, tapering, slightly curved, sharp 
spines, appressed closely to side of ray, those of outer half of ray extending obliquely over, and resting 
on, the abactinal area. On first and second inferomarginals the tumidity is not so pronounced as on 
the, rest, and the spines are shorter. On first plate there is a dorso-ventral series of 4, rather widely 
spaced, the uppermost but one being longest, which when bent upward reaches the middle of supero- 
marginal. Occasionally only 3 short spines are present. On second plate is an oblique series of 3 or 4 
spines, exceeding the plate in length, with usually 1 or 2 odd spines set close to and on aboral side of 
the 2 upper members, and an odd spine on ventral margin. On third plate is an oblique series of 4 
(3 to 7) spines, situated nearer upper margin of plate, the lowermost 3 spines being longest (3-5 mm.). 
From fourth to eighteenth or nineteenth plates the usual number of spines is 6 to each comb (5 in 
small specimens), varying on some plates to 5 and rarely to 7. Owing to the rapid reduction in the 
size of the superomarginals, the series of spines moves more and more abactinad, so that on the outer 
two-thirds of ray the bases of most of the spines can be seen when the specimen is observed directly 
from above. The longest spine is usually second from bottom of series, and the uppermost is shortest. 
The spines reach their maximum length about two-thirds the distance from base of ray, where they 
attain 7 mm. in length (about one-ninth of R), and are fairly long to within 5 or 6 plates of the 
extremity. General surface of plates is covered with minute papilliform spinelets, similar to those of 
the superomarginals, but a trifle longer on lower portion of plates. 
Adambulacral plates are massive, set obliquely, with an angular margin to furrow; slightly wider 
than long in basal half of ray; longer than wide in distal half. Armature rather crowded and some- 
what variable; in general as follows: (1) A furrow series proper of 3 long, diverging spinelets, the 
median longest and much flattened, saber-like,- the edge to furrow. The lateral spinelets are alsc 
somewhat compressed at base. With these are usually associated 2 actinal spinelets, 1 at either end 
of the series, which are really the lateral members of the first actinal series but on account of the 
extreme angularity of the furrow margin appear to belong to the furrow group, and toward the extrem- 
ity of ray the distalmost spinelet of the second actinal series also stands on the furrow margin, making 
uniform in size. Paxillse are small, smallest in central portion of disk, and are widely spaced, giving 
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Superomarginal plates, about 28 in number from interradial line to tip of ray, are very much' 
smaller. They decrease rapidly in size toward tip of ray, much more rapidly than inferomarginals, 
