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45
og staa ved de brede Grunddele saa vidt fra livetandre,
at Interbrachialrummene danne en stump Vinkel. Saavel
Skivens som Armenes Rygflade er besat med Paxiller, der
ere korte, cylindriske, næsten tvers afskaarne, bærende
mange Kalknaale. Disse Paxiller staa temmelig vidt fra
hverandre, ere uregelmæssigt stillede paa Skiven, imedens
de paa Armene danne mere eller mindre regelmæssige Rækker.
Over hele Skivens Ryg findes i hvert Paxillarfelt 8—
10 cylindriske Respirationsrør, der som oftest sidde omkring
Paxillerne. Paa Armene ere de endnu langt sparsommere,
kun 1—2, høist 3 ved Grunden af hver Paxille.
Paa hver Siderand af Armene, nærmest Bugfladen,
staar en Række 12—13 store, fremragende Paxiller, der
have et fladtrykt Skaft og paa Enden en stor Samling af
Kalknaale, Tab. IX, fig. 9.
Madreporpladen, der er lidt aflang, findes imellem
Skivens Centrum og en af Armvinklerne, dog nærmere
denne.
Bugen er flad med brede Interbrachialrum, der ere
tæt besatte med større og mindre Paxiller, og langs
Ambulacralfuren findes paa hver Side en Række Kalkpigge,
der udgaa fra den indre Del af Ambulacralpladernes undre
Rand. Af disse Kalkpigge er der (>—7 i Antal, hvilke
ved Grunden ere sammenbundne ved en fibrøs Membran,
men artikulere med Adambulacralpladen, Tab. IX, Fig. 14, a.
De ere stillede paa langs og bueformigt, saa at de
midterste ere de længste, og naar de bevæges mod
Bugfuren, støde de sammen med de tilsvarende fra. den anden
Side, saaledes, at de gribe i hverandre og derved ganske
dække Bugfuren. Foruden disse Kalkpigge, der staa
paa-langs af Bugfuren, udgaa der fra dennes ydre Rand
Tver-rækker af Kalkpigge, der tage deres Udspring fra den ydre
Del af Adambulacralpladernes undre Rand, med hvilken
de artikulere, Tab. IX, Fig. 14, b.
Hver Tverrække har især paa Midten af Armen 8 —
10 Kalkpigge, der i Almindelighed ere lige lange, Tab. IX,
Fig. 14.
Ryggens Hudskelet bestaar af smaa, aflange
Kalkstykker, der lægge sig sammen og danne kortere og
længere Kalkstykker, som anastomosere med hverandre,
hvorved et Netværk fremkommer med temmelig vidé Masker,
dog langtfra saa vide, som hos Solaster papposus.
Kalknettet er nemlig hos Solast, affinis bygget baade tættere
og finere end hos S. papposus. I Maskerne ere dels
enkelte, dels flere Kalkkorn leirede, Tab. IX, Fig. 7, a. Der
er kun Antydninger til dorsale Randplader.
Bugens Hudskelet bestaar af meget langstrakte, i
Enderne tilspidsede Kalkstykker, der ligge i tætte, uregelmæs-
short rays, which are placed with their broad origins so
far apart, that the angles formed between the rays are
obtuse. The abactinal surface, of both the disk and the
rays, is beset with short, cylindric, almost truly truncate,
paxillæ, which carry numerous calcareous spiculæ. These
paxillæ are situated considerably apart, and are irregular
upon the disk, whilst, on the rays, they form series more
or less regular.
Over the whole of the abactinal disk, there is found
in each paxillar area, 8—10 cylindrical tentacular tubes,
which are, most frequently, seated around the paxillæ.
They are still less numerous upon the rays, amounting,
only, to 1 —2 or at most 3, tentacular tubes, placed at the
base of each paxilla.
On each lateral margin of the rays, and nearest to
the actinal surface, there is situated a series of 12—13
large projecting paxillæ, having a flattened peduncle, and
upon whose extremity there is a large collection of
calcareous spiculæ (Pl. VIII, tig. 11).
The madreporite is slightly oblong, and is situated
between the diskal centre and one of the interbrachial
angles, but nearest to the latter.
The actinal surface is flat; with broad interbrachial
spaces, which are closely beset with larger or smaller
paxillæ, and along each of the lateral margins of the
ambulacral furrow, there is seen a series of calcareous spines,
which proceeds from the inner portion of the inferior margin
of the ambulacral plates. 6—7 of these calcareous spines
are bound together at the base, by a fibrous membrane,
but, are free to articulate with the adambulacral plate (PI.
IX, fig. 14, a).
This series of 6—7 spines is placed lengthwise; and
they are arcuated in such a manner, that the mesial
spines are the longest. When folded over the ventral
furrow, upon the corresponding spines of the opposite furrow
margin, they interlace, and completely cover the ventral
furrow. Besides these calcareous spines along the ventral
furrow, there proceed from its exterior margin, transverse
series of calcareous spines, which have their origin in the
inferior margin of the exterior part of the adambulacral
plates with which they articulate (Pl. IX, fig. 14, b).
Every transverse series has, especially, on the mesial
part of the ray, 8—10 calcareous spines, which are, usually,
of one uniform length (Pl. IX, fig. 14).
The abactinal dermal skeleton consists, of small
oblong, calcareous ossicles, which, by joining together, form
shorter or longer calcareous pieces, which anastomoze
with each other, producing a reticulation with
rather wide meshes, but still, not nearly so wide as in
Solaster papposus. The calcareous reticulation in Solaster
affinis, is, in fact, constructed both closer and slenderer,
than in Solaster papposus. In the meshes, calcareous grains
are seen, entrenched, partly singly, and partly, several
together (Pl. IX, fig. 7, a). There are only slight
indications of dorso-marginal plates.
Tke actinal dermal skeleton consists, of very elongate,
calcareous ossicles with acuminate extremities, placed upon
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