144 



at kun et meget begrændset Antal Familier har været op- 

 stillct; 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 Bear- 

 beidelsen af de nordiske Pycnogonideer har jeg fundet det 

 nødvendigt aøiere at præcisere ikke blot Slægterne, men 

 ogsaa Familierne, og har idethele, som det vil sees, tåget 

 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 fineler nu hertil 

 at maatte føie endnu en ny Familie, idet Slægten Phoxi- 

 rh/Jiis synes mig ved nærmere Overveielse neppe at kvmne 

 forenes med Sl. Pycnogonum i en og samme Familie, men 

 bør danne Typen for en særskilt saadan, Phoxichilidæ. 

 Antallet ai 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 fineler imidlertid nu 

 at burde forsoge 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 Saxlem- 

 merne. Hos en Gruppe af Pycnogonideer mangler disse 

 (ligesom ogsaa Følerne) fuldstændigt, naar undtages i Larve- 

 tilstanden; hos en anden Gruppe er de derimod vel ud- 

 viklede gjennem hele Dyrets Levetid; hos en tredie Gruppe 

 endelig er disse Lemmer vistnok i Regelen tilstede i Ung- 

 dommen (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 ifølge ovenstaaende Inddeling sammen- 

 stille paa følgende Maade: 



Ordo I. 

 Aehelata. 



Fam. 1. Pycnogonidæ. 



Gen. 1. Pycnogonum. 

 Fam. 2. Phoxichilidæ 



Gen. 2. Phoxichilus. 



Fam. 



Ordo II. 

 Evichelata. 



Phoxichilidiidæ. 

 Gen. 1. Phoxichilidium. 

 2. Anoplodactylus. 



that only a very limited number of families has been 

 established ; indeed, it is only first in quite late times that 

 tliere 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. tåken 

 those last in. altogether, a considerably narrower limitation 

 than other naturalists have done. Their number has, con- 

 sequently. 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 adel to this yet another, new 

 family, inasmuch that the genus Phoxichilus appears. to 

 me, on closer consideration, to be searcely 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 in- 

 dicate the greater or lesser degree of affinity they mutually 

 show among themselves. I think, however, now. that I 

 ought to attempt to still more definitely establish the 

 mutual relations between the families, by grouping them 

 in 3 large elivisions. 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 

 seeond 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 there- 

 fore) but, on tbe contrary, they, in the fully developed 

 condition, become either reduced to useless appendices. or 

 quite, and absolutely, disappear. According to this. there- 

 fore, we obtain 3 great elivisions or orders, within which 

 all the known Pycnogonids permit themselves to be ar- 

 ranged. 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. 

 _A.elielata. 

 Fam. 1. Pycnogonidæ. 



Gen. 1 . Pycnogonum. 



Fam. 2. Phoxichilidæ. 



Gen. 2. Phoxichilus. 



Fa 



Order II. 

 Knclielata. 



1. Phoxichilidiidæ. 



Gen. 1. Phoxichilidium. 

 ,. 2. Anoplodactylus. 



