121 



musklerne meget mere fremtrædende og indtage begge Sider 

 af Septumet, Tab. XXI. Fig. 18 /; Tab. XXII. Fig. 6 a. 

 saa at de skjule næsten ganske Tvermuskleme. Disse 

 Længdemuskler danne egentlig ikke nogen Fane; thi de 

 Bindevævsforlængelser, der uclgaa fra Septumets Bindevævs- 

 laniel, og som bære Længdemusklerne, ere temmelig korte. 

 Samtlige Macrosepta Bære Mesenterialfilamenter og Genera- 

 tionsorganer. 



Mesenterialfilanienterne tåge deres Begyndelse fra 

 Svælgrørets nederste, fri Ende, Tab. XXI. Fig. 16 e; Tab. 

 X XII. Fig. 4 /, hvor de udspringe med et nyreformet, 

 kjertelagtigt Organ, Tab. XXII, Fig. 5 a, der er forholdsvis 

 meget bredt, og som indad har en temmelig dyb Længde- 

 fure. Tab. XXII, Fig. 5 6. Dette Organ, der fandtes hos 

 alle de Dyr. jeg undersogte, bestaar af regelmæssigt ved 

 Siden af hinanden stillede Cylinderceller, som ere smale 

 ved deres Tilhæftning udåd til Bindevævet, men bredest 

 indad, have en temmelig stor Kjerne, der er omgiven af 

 en kornet Protoplasmamasse, Tab. XXII, Fig. be. Organel 

 tilhører aabenbart Mesenterialfilamentet og udgjor en Del 

 af det; thi Overgangen er meget tydelig. Tab. XXII, 

 Fig. 5 d. Mesenterialfilamentet bliver nu meget smalere, 

 slynger sig nedover til den nederste Trediedel ai Gastral- 

 hulheden, følgende Macroseptet og bundet til dettes Binde- 

 væv ved en tynd Membran. Mesenterialfilamentet har for- 

 resten ingen særegen Organisation ; det er udvendigt beklædt 

 med et eilierende Oylinderepithel, hvorimellem tindes en 

 Mængde Nematocyster. 



Ved Siden af Mesenterialfilamentet. men indenfor, 

 nærmere Septumets Insertion tæt ved Kropsvæggen, ligger 

 Generationsorganerne. De fleste Individer, jeg undersogte, 

 vare Hunner, kun et Dyr, der tilhørte en anden Gruppe 

 end de, hvori Hunnerne fandtes. var en Han. Kjønnet er 

 adskilt. Æggestokken udspringer ligeledes ved Svælgrørets 

 nederste fri Ende. men lidt nedenfor Mesenterialfilamentet, 

 Tab. XXII. Fig. 5 e, danner et lidt fladtrykt Ror, der 

 slynger sig proptrækkerformigt nedover langs Mesenterial- 

 filamentet, tæt til dette og indeholder Æg, kun lidet ud- 

 viklede. liggende to ved Siden af hianden, Tall. XXI. Fig. 

 17 c; Tab. XXII. Fig. 5/. Æggene ere næsten eliptiske 

 og temmelig klare. Æggestokken strækker sig i Alminde- 

 lighed lidt nedenfor Mesenterialfilamentet og er ligesom 

 dette udvendig beklædt med et Endothel af eilierende 

 Cylinderceller. men uden Nematocyster. 



Testiklerne have baade samme Form og samme Sæde 

 som Æggestokkene ; men istedetfor Æg saaes i det Indre 

 af Roret runde Celler, der lieklædte den indre Væg, samt 

 en Mængde smaa, glindsende, runde Legemer — begyn- 

 dende Spermatozoer. Hannerne ere ifølge mine Under- 

 søgelser meget sjeldnere end Hunnerne. Det er at be- 

 mærke. at Generationsorganerne ligge indenfor Mesen- 

 terialfilamenterne, aærmere Kropsvæggen, hvilket er mod- 



Den nurske Nordhavsexpedition. D. C. Datiielssen : Actinida. 



and longitudinal muscles. Whilst the transversal muscles 

 are little developed, the longitudinal muscles are much 

 more prominent and occupy both sides of the septum (Pl. 

 XXI, fig. 18 /; Pl. XXII, fig. 6 a), so that they almosl 

 conceal the transversal muscles. These longitudinal mus- 

 cles do not really form any flag, because the connective- 

 tissue prolongations that issne from the connective-tissue 

 lamella' of the septum, and which carry the longitudinal 

 muscles. are rather short. All the macrosepta carry mes- 

 enterial filaments and reproductive organs. 



The mesenterial filaments have their origin on the 

 lowest free extremity of the gullet-tube (Pl. XXI, fig. 16 e; 

 Pl. XXII, fig. 4/). where they issue in the form of a kidney- 

 shaped, glandulous organ (Pl. XXII, fig. 5 a), which, 

 relatively, is very broad, and inwards has a rather deep 

 longitudinal furrow (Pl. XXII, fig. 5 b). This organ, which 

 was present in all the animals I investigated, consists of 

 cylinder-cells placed in regular arrangement alongside each 

 other; they are narrow at their attachment outwards to 

 the connective-tissue, and broadest inwards. and liave a 

 pretty large nucleus surrounded by a granular protoplasmic 

 substance (Pl. XXII, fig. 5 c). The organ evidently per- 

 tains to the mesenterial filament and forms a part of it. 

 as the transition is very distinct (Pl. XXII, fig. 5 cl). 

 The mesenterial filament becomes then much narrower, 

 twines itself downwards to the lowest third part of the 

 gastral cavity, following the macroseptum and attached 

 to its connective-tissue by a thin membrane. Tlie mesen- 

 terial filament has, otherwise, no peculiar organisation; 

 it is externally clad with a eiliating cylinder-epithelium. 

 between whose cells a multitude of nematocysts are found. 



At the side of the mesenterial filament, but inside 

 nearer the insertion of the septum, close to the w all of 

 the body, lie the reproductive organs. Most of the indi- 

 viduals I examined were females, only one animal, which 

 pertained to another group than the one in which the 

 females were found. was a male. The sexes are separated. 

 The ovarv. a Isn. originates at the lowest free extremity of 

 the gullet-tube, but a little below the mesenterial "filament 

 (Pl. XXII, fig. oe); it forms a slightly flattened tube 

 that twines itself spirally downwards along the mesenterial 

 filament and close to it . and it contains ova only little- 

 developed, placed two alongside each other (Pl. XXI, fig. 

 7 c; Pl. XXII, fig. 5 /). The ova are almost elliptical 

 and rather pellueid. The ovary extends itself, usually, a 

 little way below the mesenterial filament, and is, like it, 

 clad externally with an endothelium of eiliating cylinder- 

 cells, but lias no nematocysts. 



The testicles have both the same fonn and the same 

 situation as the ovaries, but instead of ova round cells 

 were observed in the interiør of the tube. clothing its 

 inner wall, also a multitude of small, shilling, round cor- 

 puscles — rudimentary spermatozoa. Males are, according 

 to my observations, much more rare than females. It is 

 to be remarked, that the reproductive organs lie to the 

 inside of the mesenterial filaments. nearer to the wall of 



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