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53
næsten runde og støde til hverandre, uden egentlig at være
taglagte, som f. Ex. hos Sol. papposus og affinis, Tab.5IX,
Fig. 7, b, dels ere de mere flade, kantede og dække
hverandre (taglagte) som hos Sol. endeca, glacialis og Jurcifer,
Tab. IX, Fig. 5, d. 9, d; men heller ikke disse
Forskjelligheder kunne tjene som Slægtsinærker, hvilke heller ikke
Viguier har opstillet som saadanne.
Paxillerne, der bæres af Kalknettet, ere hos de
forskjellige Arter stillede tættere sammen eller længere fra
hverandre, som oftest eftersom Maskerne ere større eller
mindre; videst ere de hos Solaster papposus, tættest hos
S. endeca-, Overgangene findes tydeligt nok hos de 3
mellemliggende Arter: Solaster affinis, furcifer og glacialis.
Og hvad nu deres Form og Udstyr betræffer, saa finder
man ogsaa her Overgange, der vel kan hjælpe til at
bestemme Arten, men ingelunde Slægten. Hos Sol. papposus
ere de længst, [have de længste, penselformige Kalknaale;
hos S. affinis ere de kortere, hos furcifer og glacialis ere
de endnu kortere, men kortest ere de hos S. endeca.
Professor F. J. Bell,1 der har beskjæftiget sig med
Slægten Solaster, er tilbøielig til at give Dr. Viguier
Medhold i sine Udtalelser mod Agassiz’s Deling, men
udtrykker sig dog forbeholdent, idet han siger: „but that
excellent investigator seems to me to have not fully weighed
all the facts, which can be made out with regard to these
two forms, which he returns in one genus." Han ytrer
fremdeles, at den Omstændighed, at Solaster endeca liar
alene ventrale og Solaster papposus kun dorsale
Rand-plader, maa tjene som en „very considerable support"
for Agassiz’s Mening. Dersom dette virkelig forholdt sig
saa, skulde vi indrømme, at der var nogen Berettigelse til
at foretage en Deling, omendskjønt vi ikke kunne
erkjende, at denne Særegenhed ved Randpladerne alene var
tilstrækkelig Grund til Slægtens Deling. Paa de 5 Arter,
der have staaet til vor Raadighed, have vi underkaset
Skeletdelene en meget nøiagtig Undersøgelse, og vi skulle nu
angive, hvad vi have fundet med Hensyn til Randpladerne.
Hos Solaster endeca er der to Rækker Randplader,
en der tilhører Rygsiden og en Bugfladen. De ligge skjulte
af den tykke Hud og iagttages kun, naar denne tilligemed
Paxillerne er borttagen.
De dorsale Randplader ere fladtrykte, have en
trekantet Figur med den smalere Del vendt udad, Tab. IX,
Fig. 13, c; paa denne smalere Dels undre Flade er en
liden, knopformig Forhøining, der danner Ledfladen for
Paxillen. Den bredere Del vender indad og hviler med
sin øvre, lidt konkave Flade paa den tilsvarende ventrale
piates, which are partly, oblong, and partly, nearly circular,
and they abut upon each other, without, however, being
laid imbricately, as for instance, in Solaster papposus and
affinis-, (Pl. IX, fig. 7, b) they are also, partly, more flat
and angular, and cover each other imbricately as in
Solaster endeca, glacialis and furcifer (Pl. IX, fig. 5, d. 9, d),
but these divergencies cannot serve as generic features, and
neither has Viguier presented them as such.
In the various species, the paxillæ carried by the
calcareous reticulation, are placed at intervals more or less
apart, usually, according as the meshes are larger or
smaller, and they are widest in Solaster papposus, and
narrowest in Solaster endeca. The transitions are visible,
distinctly enough, in the three intermediate species Solaster
affinis, furcifer, and glacialis. Now, in regard also, to the
fonn and equipment of the paxillæ, we find transitions
which may well assist in determining the species, but not
at all the genus. In Solaster papposus, the paxillæ are
longest, and have the longest penicilliform calcareous
needles. In Solaster affinis, the paxillæ are shorter, and
in jurcifer, and glacialis, they are still shorter, but they are
shortest of all, in Solaster endeca.
Professor F. J. Bell, who has occupied himself with
the genus Solaster, is disposed to agree with Dr. Viguier in
his opinion against Agassiz’s sub-division, but he, yet,
expresses himself with reserve, in as much as he says:1 „but"
„that excellent investigator seems to me to have not fully"
„weighed all the facts which can he made out with re-"
„gard to these two forms which he returns in one genus"
— he states further, that the circumstance, that Solaster
endeca has only ventro-marginal plates, whilst Solaster
papposus has only dorso-marginal plates, must serve as a „very"
„considerable support" for Agassiz’s opinion. If this was
really the case, we would admit, that there was some
ground for making a subdivision, although, we could not
acknowledge that the peculiarity in respect of the marginal
plates, was, of itself, a sufficient reason for the subdivision
of the genus. We have instituted a close examination, of
the five species which we have had at our disposal, and
shall now state the result of our observations in regard
to the marginal plates.
In Solaster endeca, there åre two series of marginal
plates, one pertaining to the abactinal surface, and the
other to the actinal surface, and they lie concealed by the
thick integument, and become visible, only, after the
integument and the paxillæ are removed.
The dorso-marginal plates are flattened, and have a
triangular shape, with their acuminate part turned
outwards (Pl. IX, fig. 13, c). On the inferior surface of the
acuminate part, there occurs a small knob-formed
prominence, forming the articulatory surface for the paxilla. The
broad part of the plate turns inwards, and rests with its
’ A Note on the Characters of the Genas Crossaster, with the
description of a new species. F. Jeffrey Bell. Ann. & Magaz. of
Nat. Hist., 5th Ser., Vol. 8, pag. 140. 1881.
1 A Note on the Characters of the genus Crossaster with the
description of a new species, F. Jeffrey Bell. Ann. & Magaz. of
Nat. Hist. 5th Ser. Vol. 8, pag. 140. 1881.
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