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6
Fig.- 7, e. Midtpartiet forlænger sig opad imod Midtdelen
af de øverste Interbrachialplader, Fig. 9, g. Fra deres
nederste Ende udgaa ligeledes 3 Processer, en til hver
Side, Fig. 9, h, og en i Midten, Fig. 9, i.
Sideprocesserne ere meget brede og lange, gaa til Siderne udad og
nedad under Armene, hvor de fæste sig til den anden
Adambulacralplade paa hver Side af to Arme, Fig. 9, h.
Den midterste Proces derimod bøier sig indad og under
mod Munden, hvor den slutter sig til Mundvinkelpladen (de
første Adambulacralplader fra to tilgrændsende Arme).
Samtlige disse Kalkstykker bindes til hverandre ved Hjælp
af den indvendige, membranøse Ryghud, der danner’
ligesom Ligamenter om Saramenføiningerne.
Foruden de ovenbeskrevne Anal- og 1ste
Brachial-paxiller, der for endel indtage Ryggens Centrum, lindes der
langs hver Side af Annenes Ryg 8—10 Par Paxiller, Fig.
1. 9, af hvilke omtrent Halvparten nærme sig Armens
Midtlinie og danne en indre Række, Fig. 9, k, imedens de
øvrige, der danne den ydre Række, Fig. 9, l, strække sig
udover Interbrachialrummet.
Paxillerne i den ydre Række adskille sig fra dem i’
den indre derved, at Basaldelen har to Rødder. Af disse
Paxiller er den inderste, nærmest Armvinkelen den
største; dens Basaldel har to meget lange, krumbøiede
Rødder, hvoraf den ydre, Fig. 9, m. strækker sig hen til den
underste Interbrachialplade, til hvis underste Sideproces,
Fig. 9, h, den fæster sig, imedens den indre Rod, Fig. 9, n,
støtter sig til Tverprocessen af den 4de og 5te
Ambulacral-plade, Fig. 9, o. Herved dannes et aflangt Rum paa
Siden af Armens Grunddel, hvilket begrændses udad af den
2den Armpaxilles Basaldel og indad mod Armens Midte
af Ambulacralpladerne, og hvori Æggestokken eller
Testikelen er placeret. De øvrige Armpaxiller i den ydre
Række ere kortere, deres Basaldel har to kortere,
krumbøiede Rødder, hvoraf den ydre, Fig. 9, p, fæster sig paa
Adambulacralpladerne, imedens den indre, fig. 9, q, paa
Ambulacralpladens Tverproces. Rødderne ere stillede
saaledes, at de danne en Bue. Skaftet paa disse Paxiller er
ved Grunden rundt, men fladtrykt paa Midten, Fig. 9, l,
og har paa sin brede, halvrunde Ende smaa
Articula-tionsflader for de 7, (4 lange og 3 korte) Kalknaale, der
sidde i en aflang Krands og vifteformigt udbrede sig i
In-terbrachialrummenes Ryghud, Fig. 1, c. 9, r.
Paxillerne i den indre Række, Fig. 9, k, have en
udelt, fladtrykt Basaldel, Fig. 9, s, hvis indre, lidt konkave
Flade fæster sig til den indre Rod af Basaldelen i den
ydre Række Paxiller, Fig. 9, q. Skaftet paa de indre
of the five superior interbrachial plates (Pl. XIII, fig. 9, c)
and also, with the exterior roots of the first brachial
paxillæ (Pl. XIII, fig. 7, e). The mesial part is prolonged
upwards, towards the mesial part of the superior
interbrachial plate (Pl. XIII, fig. 9, g). From their lower
extremity proceed, likewise, three processes, one to each
lateral margin (Pl. XIII, fig. 9, h), and one in the middle
(Pl. XIII, fig. 9, i). The lateral processes are very broad
and long, extending to the margins, outwards and
downwards below the rays; where, they become secured to the
second adambulacral plate on each margin of two rays (PI.
XIII, fig. 9, h). The mesial process on the contrary;
curves inwards and downwards, towards the oral aperture,
and there, joins the oral angle-plate (the first adambulacral
plates from two adjoining rays). All of these calcareous
ossicles are united to each other, by means of the internal
membranous dorsal integument; forming, as it were,
ligaments round the unions.
Besides the previously described anal, and first
brachial paxillæ, which, partly, include the abactinal disks middle
part; 8—10 pairs of paxillæ (Pl. XIII, fig. 1—9) are
situated along each abactinal margin of the rays, and about
the half of these approach the mesial line of the ray,
forming an inner series (Pl. XIII, fig. 9, k); whilst the
remainder forming the outer series (Pl. XIII, fig. 9, I),
spread themselves over the interbrachial space.
The paxillæ in the outer series, differ from those of
the inner series, in the basal part having two roots. The
inner one, nearest to the brachial angle, is the largest, and
it’s basal part has two very large curved roots, the
exterior one of which, (Pl. XIII, fig. 9, m) extends to the
inferior interbrachial plate, and is secured to it’s inferior
lateral process (Pl. XIII, fig. 9, h). The interior one (PI.
XIII, fig. 9, n), abuts on the transverse processes of the
fourth and fifth ambulacral plates (Pl. XIII, fig. 9, o). In
this manner, an oblong space is formed on the lateral
origin of the rays; exterioiiy defined, by the basal part of
the second brachial paxilla, and interiorly, towards the
mesial part of the ray, by the ambulacral plates. In the
oblong space thus formed, are placed, the ovaries or
testicles. The other brachial paxillæ in the outer series are
shorter, and their basal part has two short curved roots, of
which, the exterior one (Pl. XIII, fig. 9, p) is secured to
the adambulacral plates, whilst, the interior one (Pl. XIII,
fig. 9, q) is secured to the ambulacral plates transverse
process. The roots are so placed, that they form an arc.
The shaft of these paxillæ is round at the base, but
flattened in the middle (Pl. XIII, fig. 9, I) and it has small
articulatory surfaces upon its broad semi-circular
extremity, for the 7 (4 long ones and 3 short ones) calcareous
needles, which are placed in an oblong wreath, spreading
like a fan, in the dorsal integument of the interbrachial
spaces (PI. XIII, fig. 1, c. 9, r).
The paxillæ in the inner series (Pl. XIII, fig. 9, k),
have a compact, flattened basal part (Pl. XIII, fig. 9, s),
whose inner, slightly concave, surface, is secured to the
inner root of the basal part, in the exterior paxillar series
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