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144
at kun et meget begrændset Antal Familier har været
opstillet; ja det er egentlig forst i den allernyeste Tid at
der overhovedet har været Tale om nogen Sondring mellem
forskjellige Familier inden denne Dyrgruppe. Ved
Bearbeidelsen af de nordiske Pycnogonideer har jeg fundet det
nødvendigt nøiere at præcisere ikke blot Slægterne, men
ogsaa Familierne, og har idethele, som det vil sees, taget
disse sidste i en betydelig snævrere Begrændsning end af
andre Forskere gjort. Folgen heraf er, at deres Tal er
bleven betydelig forøget. • Medens Hoek. i sine nyeste
Arbeider over disse Dyr, kun opstiller 4 Familier, er deres
Tal i nærværende Arbeide fordoblet; ja jeg finder nu hertil
at maatte føie endnu en ny Familie, idet Slægten
Phoxi-chilus synes mig ved nærmere Overveielse neppe at kunne
forenes med SI. Pycnogomum i en og samme Familie, men
bør danne Typen for en særskilt saadan, PhoxichilidoB.
Antallet al Familier, i den Begrændsning hvori jeg her
tager dem. bliver altsaa ialt ikke mindre end 9. De er i
nærværende Arbeide opførte i en bestemt Rækkefølge,
hvorved jeg har villet antyde den større eller mindre Grad
af Affinitet, de viser indbyrdes. Jeg finder imidlertid nu
at burde forsøge endnu mere bestemt at fastsætte dette
indbyrdes Forhold mellem Familierne ved at gruppere dem
under 3 større Afdelinger. Som Distinctionscharacter har
jeg herved hovedsageligt benyttet Forholdet af
Saxlemmerne. Hos en Gruppe af Pycnogonideer mangler disse
(ligesom ogsaa Følerne) fuldstændigt, naar undtages i
Larve-tilstanden; hos en anden Gruppe er de derimod vel
udviklede gjennem hele Dyrets Levetid; hos en tredie Gruppe
endelig er disse Lemmer vistnok i Regelen tilstede i
Ungdommen (altsaa ikke blot i Larvetilstanden), hvorimod de
i den fuldt udviklede Tilstand enten reduceres til unyttige
Appendices eller ganske og aldeles forsvinder. Herefter
faar vi altsaa 3 store Afdelinger eller Ordener, hvorunder
alle bekjendte Pycnogonideer lader sig indordne. De i
det foregaaende nærmere omtalte nordiske
Pycnogonide-Slægter lader sig ifolge ovenstaaende Inddeling
sammenstille paa følgende Maade:
I
Ordo I
Achelata.
Fam. 1. Pycnogonidæ.
Gen. 1. Pycnogouum.
Fam. 2. Phoriehilidæ
Gen. 2. Phoxichilus.
that only a very limited number of families has been
established; indeed, it is only first in quite late times that
there has been any mention at all of a separation between
the different families included in this animal group. In
the treatment of the northern Pycnogonids I have found
it necessary to define more minutely, not only the genera
but also the families, and have, as will be seen, taken
those last in. altogether, a considerably narrower limitation
than other naturalists have done. Their number has,
consequently, been considerably increased. While Hoek. in
his latest work on those animals, only establishes 4 families,
their number has been doubled in the present work; indeed
I now find it necessary to add to this yet another, new
family, inasmuch that the genus Phoxichilus appears, to
me, on closer consideration, to be scarcely alliable with
the genus Pycnogonum in one and the. same family, but
ought to form the type of a separate one, Phoxichilidæ.
The number of families, within the limitation in which I
here take them, becomes consequently, altogether, not less
than 9. They are in the present work arranged in a
definite consecutive order, by which I have desired to
indicate the greater or lesser degree of affinity they mutually
show among themselves. I think, however, now. that 1
ought to attempt to still more .definitely establish the
mutual relations between the families, by grouping them
in 3 large divisions. As distinctive characters I have, in
doing so, principally adopted the relations of the chelifori.
In one group of Pycnogonids these are entirely awanting
(as well as also the palpi) except in the larval state; in a
second group, they are, on the other hand, well developed
throughout the entire existence of the animal; finally, in
a third group, those limbs are certainly, as a rule, present
in the young stages (not only in the larval state
therefore) but, on the contrary, they, in the fully developed
condition, become either reduced to useless appendices, or
quite, and absolutely, disappear. According to this,
therefore, we obtain 3 great divisions or orders, within which
all the known Pycnogonids permit themselves to be
arranged. The northern genera of Pycnogonids, spoken of
in the foregoing, permit themselves, according to the
above-mentioned arrangement. to be ranked in the following
manner:
Order I.
Aclielata.
Fam. 1. Pycnogonidæ.
Gen. 1. Pycnogonum.
Fam. 2. Phoxichilidæ
Gen. 2. Phoxichilus.
Ordo II.
Knolielata.
Fam. 1. Phoxichilidiidæ.
Gen. 1. Phoxichilidium.
2. Anoplodactylus.
Order II.
Enchelata.
Fam. 1. Phoxichilidiidæ.
Geil. 1. Phoxichilidium.
,. 2. Anoplodactylus.
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