95 



septøle Ruin, Tab. XV, Fig. Ln c, imedens Tvermusklerne 

 sidde paa don indre Flade og vende mod hverandre i det 

 intraseptale Ruin. Tab. XV, Fig. 10 cl. Pan de øvrige 

 Septa ere Musklerue stillede netop modsat; saaledes eie 

 Længdeniusklerne fæstede til den indre Flade og vende 

 nu id hverandre i det intraseptale Ruin, og Tvermusklerne 

 paa den ydre Flade. vendende fra hverandre i det inter- 

 septale Ruin. 



Længdemusklerne ere i en overordentlig Grad ud- 

 viklede; de ere indtil 2""" brede, hvor de uaa Svælgrøret, 

 Tab. XV. Fig. it /'. ln c. men aftage i Bredde op imod 

 Mundskiven, paa hvis indre Flade de fæste sig. De ind- 

 tage mindst to Trediedele at' Septumets Flade, imedens 

 dennes ene Trediedel heniniod den fri (indre) Rand er 

 blottet for Muskler og danner et Længdefelt, hvori Mesen- 

 terialfilamenterne og Kjønsorganerne ere situerede. Men 

 imedens Længdemusklerne ikke ganske naa Septumets indre, 

 fri Rand, saa strække de sig udover den ydre Inser- 

 tionsrand hen paa Gastralvæggens indre Flade. Tab. XV. 

 Fig. 10/, hvortil de synes at være klæbede ved lose Binde- 

 vævstraade og bidrage til at danne de fremtrædende Længde- 

 felter iniellein Furerne, der antyde Insertionerne for Septa. 

 Længdemusklerne ere dannede af en stor Mængde Muskel- 

 libre, som ere fæstede til forgrenede Binde vævsforlængelser, 

 udgaaende fra Septum, Tab. XV, Fig. 10 e, f; de trans- 

 verselle Muskler ere forholdsvis kun lidet udviklede. ind- 

 tage saagodtsom hele Fladen af Septum og dække denne 

 i Form af en tynd, tint foldet Membran. 



Samtlige Septa bære Mesenterialfilamenter og Kjøns- 

 organer. Mesenterialfilamenterne udspringe fra den nederste 

 Del a f Svælgrøret, Tab. XV. Fig. 9 i, og folge som en 

 slangeformig Stræng den fri Rand af Septum ligetil sammes 

 bagerste Ende, Tab. XV, Fig. 9 g. Kjønsorganerne beståa 

 af i Proptrækkerform sammenrullede Baand og ere place- 

 rede indenfor Mesenterialtilamenterne, mellem disse og 

 Længdemusklerne, i den bagerste Trediedel af Gastralhul- 

 heden, Tab. XV, Fig. '.i h. De undersogte to Exemplarer 

 liavde Æggestokke, hvori Æggene i forskjellige Utviklings- 

 stadier laa i Rækker, to og to ved Siden af hinanden. Det 

 er sandsynligt, at Kjønnet er adskilt; thi Testikler vare 

 ikke at opdage. 



Svælgrøret er ganske særegent; det har temmelig 

 tykke, muskuløse Vægge, er lidt fladtrykt, stærkt foldet, 

 og paa dets' ydre Flade. der beklædes af Endothelet. lige- 

 som delt i tolv Felter, som Folge af Septainsertionerne. 

 Tab. XV, Fig. 9, imedens den dorsale og ventrale Side er 

 temmelig udvidet. hvorved hele Svælgrøret faar en næsten 

 firkantet Form, Tab. XV, Fig. 10 g ; især gjælder denne 

 Udvidning den ventrale Del, der allerede paa Svælgrørets 

 ydre Flade viser sig som et bredere Længdefelt med en 

 Fure paa, hver Side. Men paa Svælgrørets indre Flade 

 fremtræder Særegenheden tydeligere. Her viser det sig. at 

 Svælgrøret ikke som sædvanlig! danner en eneste Hulhed. 



the interseptal space (Pl. XV, fig. 10 c); whilst the trans- 

 versal muscles are seated on the inner surface and face 

 towards each other in the intraseptal space (Pl. XV, fig. 

 10 cl). Upon the remaining septa the muscles are placed 

 in exactly the reverse manner; thus, the longitudinal mus- 

 cles are secured to the inner surface and face towards 

 each other in the intraseptal space, and the transversal 

 muscles on the outer surface, facing from each other in 

 the interseptal space. 



The longitudinal muscles are developed in a very 

 high degree ; they measure up to 2'"'" in breadth at the 

 point where thev reach the gullet-tube (Pl. XV. fig. '•' /. 

 10 c), but diminish in breadth up towards the oral disc, 

 upon the inner surface of which they secure themselves. 

 They occupy at least two-thirds part of the surface of the 

 septum, whilst the remaining third part, towards the free 

 (inner) margin, is devoid of muscles and fonns a longi- 

 tudinal area. in which the mesenterial filaments and repro- 

 ductive organs are situated. But whilst the longitudinal 

 muscles do not quite reach to the inner, free margin of 

 the septum, they, vet. stretch themselves beyond the outer 

 insertional margin to the inner surface of the gastral wall 

 (Pl. XV, fig. 10 /'), to which they appear to be glued by 

 loose connective-tissue filaments, and aid in forming the 

 prominent longitudinal areas between the furrows that 

 indicate the insertions of the septa. The longitudinal 

 muscles are formed of a great multitude of muscle fibres 

 secured to the ramified connective-tissue prolongations 

 proceeding from the septum (Pl. XV, fig. 10 e, j). The 

 transversal muscles are, relatively, only little developed, 

 and occupy almost the entire surface of the septum. 

 covering it in the form of a thin fine folded membrane. 



All the septa oarry mesenterial filaments and repro- 

 ductive organs. The mesenterial filaments issne from the 

 lowest part of the gullet-tube (Pl. XV, fig. 9 i), and follow, 

 like a sinuous cord, the free margin of the septum quite 

 to its posterior extremity (Pl. XV. fig. 9 g). The repro- 

 ductive organs consist of cork-screw shaped, coiled ribbons, 

 and are situated inside of the mesenterial filaments, between 

 these and the longitudinal muscles, in the posterior third 

 part of the gastral cavity (Pl. XV, fig. 9 h). The two 

 specimens examined had ovaries. in which the ova, in 

 various stages of development, lay in series, two and two 

 alongside each other. It is probable that the sexes are 

 separated, as testicles could not be detected. 



The gullet-tube is quite peculiar; it has rather thic.k 

 musculous walls, is somewhat adpressed, strongly folded, 

 and on its external surface, which is clad with endothelium, 

 divided, as it were, into 1-' areas, in consequence of the 

 septal insertions (Pl. XV, fig. 9), whilst the dorsal and 

 ventral side is pretty much dilated, giving to the entire 

 gullet-tube an almost quadrangular form (Pl. XV, fig. 10 gj; 

 this dilation is specially prominent on the ventral part, 

 which, already on the outer surface of the gullet-tube. 

 shows itself as a broadish longitudinal area with a furrow 

 on each side. But on the inner surface of the gullet-tube 

 the peculiarity appears still more prominently. Here, it 



