Forord. 



Samtlige de paa den norske Nordhavsexpedition ind- 

 samlede Actinida ere Dybvandsformer, og en stor Del af 

 dem leve i den kolde Area. 



Actinarierne ere i sin store Almindelighed seiglivede 

 Dyr. der orientere sig temmelig let under forandrede baade 

 Livs- og Temperaturforholde. Dette i Forening med, at 

 jeg som Medlem af Expeditionen kunde ivaretage Indsam- 

 lingen og holde Dyrene længere Tid levende, hvorved de 

 i Regelen akklimatiseredes saavidt. at de i fuld Vigør ud- 

 foldede TentaMerne og foretog de Bevægelser, der ere 

 dem eiendommelige. — gjorde, at jeg fik god Tid baade 

 til at observere dem og lade dem tegne, trods den oprørte 

 Sø, som Expeditionen ofte var udsat for. 



I systematisk Henseende har jeg især fulgt den Ind- 

 deling, Professor Richard Hertwig har opstillet for de af 

 ham beskrevne Actinarier fra Challenger-Expeditionen. Som 

 bekjendt har han væsentligt lagt de anatomiske Kjendsgjer- 

 ninger til Grund for sin Inddeling og for Størstedelen 

 forladt den Methode, der af ældre Forskere er befulgt . 

 nemlig saagodtsom udelukkende at tåge Hensyn til de ydre 

 Karakterer. — ■ Imidlertid maa det erkjendes, at disse ydre 

 Kjendemærker ikke ganske bør sættes udaf Betragtning, 

 men at de meget mere maa ansees for at være ret gode 

 Hjælpémidler til at systematisere, og da jeg har havt An- 

 ledning til at iagttage Dyrene levende, har jeg ogsaa be- 

 nyttet disse ydre Karakterer, samtidig med de anatomiske 

 Kjendemærker. Saavidt jeg har formaaet, har jeg tåget 

 tilbørligt Hensyn til Gosse's og Andress Systematik, hvis 

 Arbeider over Actinarierne ere i høi Grad fortjenstfulde. 

 Men for mig har Hertwigs systematiske Inddeling været 

 mere tiltalende, end nogen Andens, forsaavidt den hviler 

 paa en mere stabil Grundvold. er ikke underkastet de 

 mangfoldige Variationer, som Tilfældet er med de ydre 

 Kjendemærker, saasom Størrelse. Hudens ydre Beskaffen- 

 hed, Farve, Tentakelantal etc. — imedens jeg fuldt ud maa 

 indrømme, at endnu er Tiden ikke inde til at kunne op- 

 stille et i alle Henseender tilfredsstillende System. Dertil 

 udfordres en mere omfattende anatomisk-histologisk Under- 

 søgelse af Actinarierne. end dor hidtil er bleven dem til Del. 



Preface. 



All the Actinida collected on the Norwegian North 

 Atlantic Expedition are deep-water forms, and a great 

 many of them dwell in the cold area. 



In general, the great bulk of the Actinaria are 

 animals very tenacious of life, which with considerable 

 facility accommodate themselves to changes of habit and 

 temperature. That eircumstance — in conjunction with the 

 fact, that as a member of the expedition I was in a position 

 to personally care for their collection and maintaiu the ani- 

 mals for a considerable time in the animate state, by which 

 they became so far acclimatized, that they in full active vigour 

 unfolded the tentacles and exercised the movements char- 

 acteristic of them — enabled me to obtain plenty of time, 

 both to observe them as well as have them drawn in 

 spite of the heavy rolling sea the expedition was frecpiently 

 exposed to. 



In regard to system, I have more particularly followed 

 the classification Professor Richard Hertwig has established 

 for the Actinaria from the Challenger Expedition which 

 he has described. As is known. he has tåken, principally, 

 the anatomical features as the basis of his classification, 

 and has abandoned, for the greater part, the method 

 adopted by the older naturalists viz. to confine attention 

 almost exclusively to the external characteristics. It must. 

 however, be aeknowledged, that those external character- 

 istics should not be entirely disregarded, but should much 

 rather be regarded as particularly valuable auxiliaries 

 in systematizing, and as I have had the opportunity of 

 observing the animals while in the animate state, I have 

 also considered those external characters along with the 

 anatomical features. So lar as it has been possible to 

 do so, I have paid due regard to Gosse's and Andres's 

 systematism — whose works on the Actinaria are in an 

 eminent degree valuable — but Hertwig's systematic clas- 

 sification has had greater attractions for me than that of 

 auy other. in so far. that it rests on a more solid found- 

 ation and is not exposed to the numerous variations per- 

 taining to external characteristics, such as size, nature of 

 the external integument, colour. number of tentacles &c. 

 whilst I must fully admit, that the time has not yet ar- 

 rived at which we can establish a — in all respects — 

 satisfactory system. For that. a wider and closer histo- 



