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96
Legemet er femarmet. Det største Exemplars G-j
en-nemsnit er 24"""; Høiden 6""". Forholdet imellem den lille
og store Radius som 1 :4. Ryggen meget hvælvet,
overalt besat med Paxiller, der staa omtrent 0.5mm fra
hverandre, Fig. 1. Analaabningen subcentral, omgiven af 5
Paxiller. Madreporpladen er lidt hvælvet, aflang og
sidder ganske i Nærheden af Anus.
Armene ere ved deres Grunddel meget smale, kun
5""", men blive efterhaanden bredere i en Udstrækning af
3—4m’n, hvor de opnaa den største Bredde, nemlig 8—9"™;
den øvrige Del af Armene, der smalner af mod Spidsen,
er 10",m lang, Fig. 3. Enhver Arms Rand danner paa sin
indre Del en Yinkel, Fig. 3, a, saaledes at Hjørnet af denne
paa den ene Arm nærmer sig stærkt til den anden Arms
tilstødende Vinkelhjørne, Fig. 3. 4, saa at en Spalte
opstaar imellem Armenes Grunddel, Fig. 3, b, hvilken
fortsætter sig i en temmelig dyb Fure paa Rygfladen, Fig. 3, c.
Paa Rygskiven ere Paxillerne stillede næsten
kreds-formig; paa Armene derimod staa de i regelmæssige
Rækker, Fig. 5, der gaa fra Armens ene Rand til den
anden. Enhver Paxille bestaar af en Samling af 6—10
meget lange, yderst spidse Kalknaale, Fig. 5, a. 6, som paa
sin nederste Del ere halvt omgivne af en Kalkskede, der
har en udvidet, halvrund, gjennembrudt Grunddel, Fig. 7, a,
som, idet den støder nøie til den tilsvarende Kalkskedes
Grunddel, danner Paxillens Basaldel, der har en rund
Ar-ticulationsflade, Fig. 6, a. Kalkskedernes Grunddele ere
stillede i en Kreds, Fig. 6, a, og ere sammenbundne meel
en stærk Bindevævsmembran, der beklædes af Huden, som
forlænger sig op over samtlige Kalkskeder, der udgjør
omtrent 1.5""" i Længde, imedens Kalknaalen, som Skeden
omfatter, er 4—5mm lang paa Skiven og Ryggen af
Armene, men kun omtrent 3mm paa Armenes Sider. Ved
denne Forlængelse af Huden opover Skederne bindes
Naalene end stærkere sammen og erholde Formen af et
Bæger. Hver Paxille er forsynet med stærke Muskelfibre,
der udbrede sig opover Basaldelen.
Paxillerne artikulere med den lille, knopformige
Ledflade, der findes paa Ryggens Kalkplader, Fig. 3, d.
Disse ere store, flade, skjælformige, omtrent ligesaa lange
som brede, med noget afrundede Rande; paa Midten ere
de kompakte og have paa derés ydre, noget ophøiede Flade
den føromtalte runde, knopformige Articulationsflade, —
imedens Pladernes Sidedele ere tynde, tildels
[gjennemsigtige, saa at det netformige i Bygningen kan iagttages, Fig.
14. Enhver Plade bærer en Paxille. Kalkpladerne paa
Siderne af Armene ere mere langstrakte, næsten ovale,
Fig. 3, e. Samtlige Kalkplader ere tæt taglagte, danne
regelmæssige Rækker, Fig. 3, der fulkommen svare til de
The body is 5-rayed. The diameter of the largest
specimen is 24mm, and its thickness is 6mm. The disk
radius bears to the brachial radius, the proportion of, as 1:4.
The abactinal surface is much arched, and is, everywhere,
beset with paxillæ, placed about 0.5mm apart from each
other (fig. 1). The anal aperture is subcentral, and
surrounded by 5 paxillæ. The madreporite is oblong, and
slightly convex, and is situated in immediate proximity to
the anus.
The rays are very narrow at their origin, being only,
here, about 5mm broad, but they become, gradually, broader,
through an extent of 3—4""" of the brachial length, and
then attain their maximum breadth of 8—9mm. The
remaining part of the rays tapers off towards the tip.
and this part is 10fflm long (fig. 3). The margin of
each ray, forms at the inner part, an angle (fig. 3, a), in
such manner, that the apex of the angle of one ray,
approaches nearly, to the apex of the corresponding angle
of the adjoining ray (figs. 3. 4) forming a fissure, thus,
between the origins of the rays (fig. 3, 6), which becomes
continued into a rather deep furrow on the abactinal
surface (fig. 3, c).
On the abactinal disk, the paxillæ are arranged in
nearly ring-form, but upon the rays, they are, on the other
hand, arranged in regular series (fig. 5), extending from one
margin of the ray to the other margin. Each paxilla
consists, of a collection of 6—10 very long, extremely
acuminate calcareous needles (fig. 5, a. 6) which, upon the lower
part, are half encased by a calcareous sheath, with a dil-.
ated semicircular perforated basal part (fig. 7, a). By
butting immediately to the corresponding calcareous sheath’s
basal part, it forms the paxillas basal part, which also,
is furnished with a circular articulatory surface (fig. 6, a).
The basal parts of the calcareous sheaths, are arranged in
a ring (fig. 6, a) and, are united together by a strong
connective-tissue membrane, which again, is covered by the
integument that extends over all the calcareous sheaths.
These are about 1.5""" in length, whilst, the’ calcareous
needles, which the sheaths encase, are 4.5""" in length on
the disk and the abactinal surface of the rays; but only
about 3mm in length, on the lateral surface of the rays.
By the extension of the integument over the sheaths, the
needles are still firmer bound together, and they acquire
the form of a chalice. Each paxilla is furnished with
strong muscular fibres, which spread up, and around its
basal part. The paxillæ articulate with the small
knob-formed articulatory surfaces found on the calcareous plates
of the abactinal surface (fig. 3, d). These are large, flat,
and scale-formed, and are about as broad as they are long,
whilst the margin is somewhat rounded. In the middle,
they are compact, and carry, on their outer, somewhat
raised surface, the previously spoken of, round, knob-formed
articulatory surfaces. The lateral surfaces of the plates
are thin, and semi-transparent, so that the reticulated
construction can be observed (fig. 14). Each plate carries a
paxilla. The calcareous plates on the lateral surfaces of
the rays, are more elongated, and nearly oval (fig. 3, e).
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