154 



Septa ere dannede af fibnllært Bindevæv, der her er 

 temmelig tykt og egentlig Fortsættelse af Kropsvæggens 

 Bindevæv og har en Muskelanordning ganske lig den hos 

 Fenja mirabilis, idet Ilegge Sider ere beklædte med longi- 

 tudinelle Muskler, imedens de transverselle. som kun ind- 

 tage en Side, synes at være lidet udviklede og dækkede at' 

 de longitudinelle Muskler. Tab. XIX. Fig. 1—4. Fra begge 

 Sider af' Septa udgaa en Mængde tynde Bindevævsgrene. 

 Tab. XIX, Fig. 1 a, og paa disse sidde Muskelfibrillerne, 

 Tab. XIX, Fig. 1 6, hvorved det Hele faar et smukt, busket 

 Udseende. Men idet Længdemusklerne udgaa fra Krops- 

 væggen for at udbrede sig paa begge Sider af Septa, sende 

 de langs deres Insertioner en Samling af stærke Muskel- 

 bundter, der danne Kropsvæggens Længdemuskler, som 

 strække sig fra den bagerste Ende til Mundskiveus Under- 

 flade, hvor de udbrede sig. Disse 12 Længdemuskler ere 

 saa brede, at de, naar Dyret er udspændt, kunne sees 

 igjennem Huden. 



Længdemusklerne, som folge begge Sider af Septa, 

 ere omtrent lige brede overalt, Tab. XIX. Fig. 2 — 4 ; men 

 henimod Spise- og Tarmrøret Ligesom vamle de sig mere 

 og afgive stærke Muskelbundter , der følge Septainser- 

 tionerne paa Digestionsapparatet, Tab. XVIII, Fig. 7 å\ 

 Tab. XIX, Fig. 1 c. Her virke de som 12 særegne Længde- 

 muskler. der bidrage til at forkorte Spise- og Tarmrøret. 



Men foruden de 12 Septa. som dele hole Kropshul- 

 heden i 12 afsluttede Længdekamre, sees paa Spise- og 

 Tarmrørets ydre Væg, imellem hver 2 Septa. en Samling 

 af listeformige Fremspring, der udgaa fra Digestionsappa- 

 ratets Bindevæv, Tab. XIX. Fig. 1 d, 2—4 b. er dannet 

 af dette og beklædes af temmelig korte, eilierende Cylin- 

 derceller. Tab. XIX. Fig. 1 e. Disse Fremspring rage 

 temmelig langt ind i Kammeret, ja i den bagerste Del af 

 Kamrene naa de næsten hen til Kropsvæggen; de ere tem- 

 melig faste og dele sig stundom gaffelformigt aden derfor 

 at tabe noget af Karakteren, Tab. XIX. Fig. 1 /. 



Jeg har gjort opmærksom paa et lignende Forhold 

 hos Fenja mirabilis; men hos denne er det dog langt fra 

 saa fremtrædende. Jeg ved ikke at sammenligne disse 

 særegne Fremspring med noget andet end med liudviklede, 

 ufuldstændige Septa. som man stundom finder hos Actinid- 

 erne ; men, vel at mærke, altid udgaaende fra Kropsvæg- 

 gen. Her, som paavist, udgaa de fra Spise- og Tarmrøret 

 hai" ingen anden histologisk Bygning end den omtalte. 

 Muskler har det ikke været mig muligt at opdage paa 

 «lisse Organer, der, saavidt jeg kan skjønne, ikke kan have 

 nogen anden Opgave end at dele Kamrene saaledes, at der 

 bliver et langt storre Fladeruin, som Ernæringsvædsken 

 kan komme i Berørelse med. Xogen korresponderende 



contraction, so that we are not in a position to form a 

 definite conclusion from it. 



The septa are formed of fibrillous connective-tissue, 

 which is here pretty thick and is really a continuation 

 of the connective-tissue of the wall of the body. with 

 a muscular arrangement quite like that of Fenja mirabilis, 

 as both sides are clad with longitudinal muscles, whilst 

 the transversal muscles, which only occupy one side, appear 

 to be little developed and are covered by the longitudinal 

 muscles (Pl. XIX, figs. 1—4). From both sides of the 

 septa a multitude of thin connective-tissue ramifications 

 issne (Pl. XIX. fig. 1 a), and on these sit the muscle- 

 fibrils (Pl. XIX, fig. 1 b). causing the whole to acquire 

 a beautiful fruticous appearance. But as the longitudinal 

 muscles issue from the wall of the body. in order to dis- 

 tribute themselves on both sides of the septa, they semi 

 along their insertions a collection of strong muscular bundles, 

 which form the longitudinal muscles of the wall of the body 

 and extend from the posterior extremity to the under surface 

 of the oral disc, where they distribute themselves. Those 

 12 longitudinal muscles are so broad, that. when the animal 

 is dilated, they may be observed through the integument. 



The longitudinal muscles. which pass along both sides 

 of the septa. ar- about uniform in breadth everywhere 

 (Pl. XIX. fig. 2—4). but towards the gullet-tube and 

 intestinal canal they, as it were, collect more together, 

 aud give off -tron- muscular bundles which accompany 

 the insertions of the septa on the digestive apparatus (Pl. 

 XVIII, fig. 7 d; Pl. \IX. fig. i C ). Here they operate 

 as 12 special, longitudinal muscles, which assisl in shortening 

 the gullet-tube and intestinal canal. 



But besides the 12 septa. which divide the entire 

 cavity of the body into 12 closed longitudinal chambers, 

 there is seen, on the exterior wall of the gullet-tube and 

 intestinal canal between each two septa. a collection of 

 fillet-formed prominences that issne from the connective- 

 tissue of the digestive-apparatus iPl. XIX. fig. 1 d. 2—4 6), 

 are formed by the connective-tissue, and are clad with 

 rather short eiliating cylinder-cells (Pl. XIX. fig. 1 e). 

 These prominences extend pretty far into the chamber, 

 indeed, in the posterior part of the chamber they extend 

 almost to the wall of the body: they are pretty tinn. and 

 sometimes divide themselves bifurcately without, however. 

 losing anything of their special cha raet er i Pl. XIX. fig. I f). 



I have called attention to a similar relation in Fenja, 

 mirabilis. but in that animal they are not uearly so pro- 

 minent. I do not know with what to compare those 

 peculiar prominences. unless it be with undeveloped, im- 

 perfect septa, such as are sometimes met with in the Actinida, 

 but, it must be remembered, always issuin>j; from the wall 

 of the body. Here, as has been shown, they issue trom 

 the gullet-tube and intestinal canal. and have no other 

 histological structure than the one spoken of. It has not 

 been possible, for me, to discover muscles on these organs, 

 which, so far as I can make out. can have no other func- 

 tion than to divide the chambers in such a manner, that 

 a far larger surface arises with which the nutritory fluids 



