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88
Udbredning.
Langs Norges Kvst, men sparsomt overalt. Den
Murmanske Kvst. Nordamerikanske Kyst. Engelske Kyst.
Archaster Parelii, varietas longobrachialis, nob.
1877. Archaster Parelii, varietas longobrachialis, Koren &
Danielssen. Nyt Magaz. f. Naturvidenskaberne
23 B. 3 H. pag. 61.
Denne Søstjerne afviger i flere Henseender temmelig
meget fra den typiske Form, uden at vi dog have troet at
burde ophøie den til en selvstændig Art.
Forholdet imellem den lille og store Radius er paa
Exemplarer af 108—124mm Diameter som 1:31/»—31/*.
Randpladerne, der paa Exemplarer af nysnævnte
Størrelse ere 38—40 i Antal, ere ved Armens Grund 4.1"""
brede, 2mm høie og Paxillarfeltet 9mm bredt; paa Midten af
Armen ere de 2mm brede, 1.5""" høie og Paxillarfeltet 2.8mm
bredt. Adambulacralpladerne ere nærmest
Ambulacralfu-ren forsynede med 4—5 indtil 6 flade, temmelig lange og
vidt fra hinanden staaende Papiller; almindeligst er der
dog 5. Mundpladerne (Maxilierne) have paa hver Side
8—9 stærke Papiller. Farven cigarbrun paa Rygfladen,
graalighvid paa Bugfladen.
Sammenholdes nu den typiske Archaster Parelii med
vor Varietet, viser det sig, at denne har en meget
bredere Skive og længere Arme, at Randpladerne ere flere
i Antal, smalere og lavere, og at Paxillarfeltet er bredere.
Adambulacralpladerne have flere og længere Pigge, hvilket
ogsaa er Tilfældet med Mundpladerne, og endelig er
Farven ganske forskjellig.
M. Sars omtaler i sin Oversigt over Norges
Echino-dermer en Varietet af Archaster Parelii, som nærmer sig
vor temmelig meget, men som dog ikke i saa betydelig
Grad som vor afviger fra den typiske Form. Sars’s
Varietet har ikke saa bred Skive og heller [ikke saa lange Arme
som vor, hvilket Forholdet mellem den lille og store
Radius bedst udviser (Sars’s Exemplar var 1 Tomme større
end vort største), Randpladerne ere færre i Antal, og
deres Breddeforhold til Paxillarfeltet er næsten omvendt af det
paa vor Varietet. Farven er som paa den typiske Art.
Unegtelig har man her for sig en Form, der synes
at ville arbeide sig op igjennem Tidernes Løb til en selv-
Distribution.
Along the Norwegian coast, but, everywhere,
sparingly. The Murman coast. The North American coast.
The British coast.
Archaster Parelii, varietas longobrachialis, nob.
1877. Archaster Parelii, varietas longobrachialis, Koren
and Danielssen. Nyt Magaz. f.
Naturvidenskaberne, 23 B. 3 H. pag. 61.
This starfish differs, widely, in several respects from
the typical form}; but we have not thought it right to raise
it to an independent species.
In specimens of 108—124mm in diameter, the
proportion of the disk-radius to the brachial radius is, as 1:
3V3—3 ’/4.
The marginal plates in specimens of the dimensions
just stated, are 38 to 40 in number; and at the origin of
the rays, they are 4.1mm broad, and 2m™ thick, and the
paxillar area is 9mffl broad. In the middle of the rays;
the paxillæ are 2mm broad, 1.5""" high, and the paxillar
area is 2.8 broad. The adambulacral plates next to the
ambulacral furrow, are furnished with 4 to 5, and
sometimes 6, flat, rather long papillæ, placed at some distance
apart from each other, but usually, there are only five of
them. The oral plates (maxillary-plates) have 8 to 9 strong
papillæ on each lateral margin. On the abactinal surface
the colour is chocolate brown, and on the actinal surface
it is greyish white.
When we now compare the typical Archaster Parelii
with our variety, it is apparent, that, is has a much broader
disk, and longer rays; and further, that the marginal plates
are more numerous, narrower, and thinner, and that the
paxillar area is greater. The adambulacral plates have longer,
and more numerous spines, and this is, also, the case with
the oral plates; and finally, the colour is quite different.
M. Sars in his „Oversigt over Norges Echinodermer",
mentions a variety of Archaster Parelii, which approaches
pretty much to our variety, but does not differ, however,
in such a marked degree as ours does, from the typical
form. Sars’ variety has not such a broad disk, or fsuch
long rays as ours. This is very apparent in the
proportion which the disk radius and brachial radius bear to
each other (Sars’ specimen was one inch larger than our
largest one). The marginal plates are fewer in number,
and their proportional breadth toj that of the paxillar area,
is almost the reverse of what it is in our variety. The
colour is similar to that of the typical species.
We have, undoubtedly, in this variety, a form which
appears as if in the course of time, it would evolve into
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