Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
39
Vi have nu leveret en nogenlunde fuldstændig
Beskrivelse af denne høist interessante Pennatulidés Ydre,
og vi have behandlet særskilt hvert Exemplar af de 12, der
ere fundne paa den norskt« Nordhavsexpetlition, væsentlig
fordi de frembyde i de forskjellige Aldere og
Udviklingsstadier Særegenheder, som, hvor kun et enkelt Specimen
haves til Raadighed, let kan lede til Antagelse af særskilte
Arter, noget, der efter vor Formening har fundet Sted
ved de af Dr. Lindahl opstillede 2 Arter, Umbellula miniacea
og Unib. pallida og sandsynligvis med Professor Köllikers
Umbellula magniflora, hvilke samtlige vi have opførte i
Synonymien. Allerede Kölliker har fundet Lindahls Arter
saa lidet adskilte fra hinanden, at han har slaaet dem sammen
under Navnet Umbellula Lindalili, og vi ere ved Sammenligning
med vore Exemplarer komne til den fuldstændige
Overbevisning, at de ere mindre udviklede (yngre) Exemplarer af clen
gamle, ærværdige Umbellula encrinus. Af vore Beskrivelser
fremgaar det formentlig med Bestemthed, at ethvert
Exemplar frembyder en eller anden Særegenhed, der staaende
for sig alene uden at kunne sammenlignes med en Række
Exemplarer i forskjellige Aldere, vil kunne benyttes som
Artsmærker, saaledes som Dr. Lindahl har gjort.
Forudsat at vi havde fundet de 12 Exemplarer igjennem et
hengere Tidsrum og kun 1 Exemplar af Gangen, havde tier
tla været for os omtrent de samme Grunde til Dannelsen
af 10 12 Arter, som der har været for Dr. Lindahl til
at danne 2. Slægten Umbellula er let kjendelig med sin
særegne, forholdsvis lange Stilk, metl sin forkrøblede
Rachis og metl de store, hængende Polyper; men Arten
encrinus er temmelig variabel, alt eftersom Exemplaret or
mere eller mindre udviklet, — og kun vetl et større
Sam-menligningsmaterial, saaledes som det vi have været saa
lykkelige at være i Besiddelse af, kan det undgaaes at
opstille nye Arter, der dog til syvende og sidst falder sammen
med den gamle encrinus.
Ser vi nu hen til vore 12 Exemplarer, tinde vi, at
Stilken varierer paa hvert enkelt; den danner foroven en
større eller mindre Bue, ofte afhængig af Polypernes Tyngde;
den er paa enkelte Exemplarer overordentlig meget dreiet
efter Længden, paa andre er tlen ganske opret og lige;
tlens nederste, bulbøse Del er forskjellig baade i Tykkelse
og Længde, stundom ganske rund, hyppig fladtrykt paa
Ventral- og Dorsalfladen, hos enkelte firkantet og ender
hyppigst som en afstumpet Konus med en ovoid
Skraa-flatle; Stilkens øverste, skedeformige Del varierer
ligeledes dels efter Exemplarets Altler. dels eftersom
Stilkens Dreininger ere mere eller mindre udstrakte.
Rachis er jo ogsaa meget forskjellig; paa enkelte
Exemplarer er tlen yderst kort og kun lidet dreiet, saa at Enden
er let at observere, paa andre er tlen længere, meget bred
og stærkt fordreiet, saa at tlen danner en tyk Klump, paa
hvilken det er ugjørligt at paavise noget egentligt Endepunkt.
We have now presented a somewhat complete
description of this highly remarkable Pennatulida’s exterior,
and have treated each specimen, of the 12 specimens
collected during the Norwegian North-Atlantic Expedition,
by itself, principally, because they display peculiarities in
the various ages and stages of devlopment, which, when
only one specimen is at disposal, may easily lead to the
adoption of separate species. This has, in our opinion,
happened with the 2 species Umbellula miniacea, antl
Umbellula pallida, established by Dr. Lindahl, and probably,
also, with Professor Köllikers Umbellula mar/ni f lor a, all
of which, we have placed in the common synonymy.
Kölliker has previously found Lindahl’s species, so little different
from each other, that be has classed them together under
the designation Umbellula Lindahl i; and, we have, after
comparison with our specimens, arrived at the complete
conviction. that they are, partially developed (younger) specimens
of the old, venerable Umbellula encrinus. From our
description, it appears, presumably, with certainty, that
each specimen presents, some one. or other peculiarity, which
taken by itself; without opportunity of comparison with a
series of specimens of different ages; may be used as
a specific characteristic, in the manner Dr. Lindahl has
done. Supposing that we had collected our 12 specimens
over a long period of time, and only one specimen at a
time, there would, then, have also been for us, about the
same reasons for the formation of 10 or 12 species, as
there has been for Dr. Lindahl to form 2 species. The
genus Umbellula is easily recognisable by it’s peculiar,
relatively long stem, with it’s scrubby rachis, and by the
large pendant polyps; but the species encriuus is pretty
variable, according, as the specimen is more or less
developed, and, only, with the assistance of an extensive
comparative material, like what we have been so fortunate to
obtain posession of, is it possible to avoid the creation of
new species, which, after all is said and done, conform to
the oltl enn-inus.
If we examine our 12 specimens, we find, that the
stem is different in each one of them. They all form at
the upper part, a larger or smaller arc, frequently
depend-dent on the weight of the polyps. In some specimens, the
stem is greatly twisted longitudinally, whilst, in other
specimens it is quite erect and straight. Its lower bulbous
part is variable, both, in thickness, and in length;
sometimes, it is quite round; frequently, it is flattened
on the ventral and dorsal surfaces. In a few specimens,
the stem is quadrangular, antl terminates, often, as a
blunted cone having an ovate diagonal surface. The
superior sheath-formed part, also varies, partly, as a
consequence of the age of the specimen, antl partly, also,
according as the twisting of the stem is more or less
extensive.
The rachis too, is very various. In a few specimens
it is extremely short, antl only slightly twisted, so that, it’s
extremity is easily detected. In other specimens, it is
longer, very broad, antl strongly twisted, so that, it forms
a thick lump, in which it is impracticable to detect any
<< prev. page << föreg. sida << >> nästa sida >> next page >>
