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55
Randplader fandtes. Samraenvoxningen er saa komplet,
at vi ikke med kaustisk Kalilud have kunnet hæve den.
De ventrale Randplader, Tab. IX, Fig. 12, b, ere
næsten laneetformige, deres bredere Del vender udad, og
dennes undre Flade afgiver et stærkt Støttepunkt for de
dorsale Randplader. Den indre, noget smalere Del,
haien konkav Overflade, der hviler paa den undre, afrundede
Rand af Adambulacralpladerne, Fig. 12, a; den undre
Flade er ujævn konvex. De ventrale Randplader bære
ingen Paxiller, men tjene udelukkende som Støtte for de
dorsale Randplader. Det falder af sig selv, at i
Inter-brachialrummene støde de ventrale Randplader umiddelbart
til Bugpladerne.
Odontophoren (Interbrachialpladen, Agassiz) frembyder
ingen nævneværdig Forskjellighed, men har saavel hos Sol.
papposus som endeca den for Slægten Solaster angivne Type.
Det egentlige Skelet er saagodtsom ens for begge
Former. Saavel Ambulacral- som Adambulcralpladerne staa
kanske lidt længere fra hverandre hos Sol. papposus, end
hos endeca; men ikke engang denne lille Forskjellighed er
konstant. Tænderne ere noget stærkere hos Sol. endeca,
end hos papposus; men forresten ere de ens. ’
Efter hvad vi have fremhævet af disse to Arters
Anatomi, fremgaar det formentlig med Bestemthed, at
Forskellighederne ikke ere større, end de nødvendigvis maa være, for
at Arterne skulle kunne opretholdes som saadanne, og at
der, ifølge vor Opfatning, ikkç bør være Tale om at dele
Slægten for de omhandlede to Arters Vedkommende.
Skulde en slig Deling finde Sted, blev det nødvendigt at
danne en egen Slægt ogsaa for vor nye Art, Sol. glacialis;
thi den kan efter den Maalestok hverken henføres til
Solaster eller Crossaster, saasom den staar omtrent midt
imellem. Den danner en Overgang fra Sol. endeca til papposus.
Man vil se, at Paxillerne hos Sol. glacialis staa
længere fra hverandre og ere lidt længere end hos endeca,
men ere hverken saa lange, eller saa spredte som hos
papposus ; at der langs Armenes Rand er en Række temmelig
store, penselformige Paxiller, der sees tydeligst fra
Rygsiden ligesom hos papposus, uden at fremtræde saa stærkt
som hos denne; imedens de paatversgaaende Paxillerækker,
der ere saa egne for Bugfladen hos Sol. endeca, langtfra
ere saa fremtrædende hos Sol. gladalis. Og ser man nu
hen til Hudskelettet, saa finder man, at cle smaa
Kalkstykker, der danne Maskenettet, have i Form og
Udbred-ning meget tilfælles meel det hos endeca; men mest
nærmer det sig dog Sol. furcifer, som det med Hensyn til
Randpladernes Anordning og Form ligner ganske. Vi
formene saaledes, at Sol. glacialis viser end yderligere
Uholdbarheden af den omtalte Deling af Slægten Solaster.
found. The growing together is so complete that a
solution of caustic potash, has been unable to effect a
separation.
The ventro-marginal plates (Pl. IX, fig. 12, b) are
almost lancet-formed, with the broad part turned outwards,
and the inferior surface affords a strong supporting point
for the dorso-marginal plates. The inner and somewhat
narrower part, has a concave surface reposing on the
inferior rounded margin of the adambulacral plates (Pl. IX,
fig. 12, a). The inferior surface is roughly convex. The
ventro-marginal plates carry no paxillæ, but serve
exclusively, as supports for the dorso-marginal plates. It follows,
naturally, that, in the interbrachial spaces, the
ventro-marginal plates abut close upon the ventral plates.
The odontophore (the interbrachial plate, — Agassiz)
presents no noteworthy divergence, but has, in Solaster
papposus, as well as, also, in Solaster endeca the normal
type pertaining to the genus Solaster.
The skeleton proper is almost exactly alike in both
forms. The ambulacral plates, and also the adambulacral
plates, are, perhaps, placed a little further apart from each
other in Solaster papposus, than in endeca, but even this
small divergence is not constant. The teeth are somewhat
stronger in Solaster endeca, than in papposus, but otherwise
they are alike.
From what we have now particularised in x-eference
to the anatomy of these two species, it may, we think, be
accepted as certain, that the divergencies are not greater
than they of necessity must be, in order to permit the
species to be maintained; and according to our view, there
ought to be no question of subdividing the genus, as far
as regards the two species referred to. Should such a
subdivision be made, it would also become necessary, to
form a special genus for our new species Solaster glacialis,
because, it can, according to this same scale, be assigned
neither to Solaster nor Crossaster, inasmuch, as it stands
about intermediately between them, and forms a transition
from Solaster endeca to Solaster papposus.
It will be’seen; that the paxillæ in Solaster glacialis
are situated more apart from each other, besides being a
little longer than in endeca; but are neither so long, nor
so dispersed as in papposus; further, that along the margin
of the rays, there occurs a series of rather large
penicilli-form paxillæ, which are seen distinctly from the abactinal
side; and this, is the case, also, in. Solaster papposus, but they
are, in endeca, not so prominent as in papposus, whilst, the
transverse paxillar series which are so peculiar to the
actinal surface of Solaster endeca, are not nearly so
prominent in Solaster glacialis. If we proceed to look at the
dermal skeleton, Ave find that the small calcareous ossicles
which form the reticulation, are, in distribution and form,
very similar to those of endeca, but yet, approach still more
closely, in similarity, to Solaster furcifer, and indeed, so much
so, in regard to the form and arrangement of the marginal
plates, that these are quite alike. We think therefore that
Solaster glacialis still further shows the untenability of the
subdivision of the genus Solaster, which has been referred to.
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