124 



Huden er gjennemsigtig, fast, stærkt opaliserende. Anal- 

 aabningen rund, og paa den forreste Trediedel af Kroppen. 

 Muskellagene ere tre: Ringmusklerne (Fig. 10 r), de 

 yderste, nærmest Huden, ere omtrent 100 i Antal; Læng- 

 demusklerne (Fig. 10 1), de inderste mod Kropshulheden 

 ere 24, og Skraamusklerne (Fig, 10 s, s), der ligge imel- 

 lem begge Lag. Ringmuskelbundterne have en Bredde 

 af 0,4 Mm., slutte sig meget tæt sammen, og vige egent- 

 lig kun fra hinanden der, hvor de ikke overskjæres af 

 Længdemusklerne. Paa Glans gaa de aldeles i hinanden. 

 Længdemusklerne (Bundterne) have en Bredde af 0.3 Mm., 

 og have lige bag til Glans et temmelig stort Mellemrum, 

 nemlig 0.6 Mm. Idet de gaa over i Volden, slutte de sig 

 tæt sammen, og imedens de yderste Fibre af hvert Bundt 

 krydse hverandre og brede sig derefter udover Glans, 

 løbe de midterste Fibre lige bagud, og blive alt sparsom- 

 mere og sparsommere mod Enden. Skraamusklerne ere 

 meget småle, 0.030 Mm., neppe flere end Halvparten saa- 

 mange som Længdemusklerne, og bestaa af 4 — 6 Fibre; 

 Bundternes Mellemrum udgjør 0.12— 0.16 Mm. De enkelte 

 Muskelfibre have en Tykkelse af 0.005 Mm., og deres Ske- 

 der ere forsynede med temmelig store Kjerner 



Retractorerne ere 4, som tage deres Udspring fra 

 den indvendige Flade af Kropshulheden paa den forreste 

 Del af dennes midterste Trediedel, ligesom parvis noget 

 bagenfor Endetarmens Aabning, saa at to tilhøre Bug- 

 fladen, to Rygfladen. Retractorerne udspringe egentlig 

 fra 4 Længdemuskler med 4 Rødder, og ere ved Udspringet 

 temmelig brede, blive lidt smalere, men indtage snart 

 sin tidligere Bredde, idet de convergerende gaa henimod 

 deres Insertionssted, Tentakelringen. 



Fordøielseskanalen dannes af en meget lang Tarm, 

 der spiralförmig slynger sig om sig selv. Den begynder 

 ved Mundaabningen temmelig smal, løber saa i næsten 

 lige Linie bag til Høiden af Analaabningen, nu tiltager 

 den noget i Tykkelse, og gjør en svag Sidekrumning til 

 Midten af Kropshulheden, hvor den danner en Slynge, 

 stiger saa igjen fortil, danner atter en Slynge, for der- 

 efter at løbe i Bugtninger mod Enden af Kropshulheden. 

 Her bøier den sig paany fortil, slyngende sig omkring 

 den bagtil gaaende Tarmdel, indtil den kommer henimod 

 den første Slynge, som den gaar over, derpaa løber den 

 under den anden og forreste Slynge, bliver nu noget sma- 

 lere (Rectum Fig. 8 re) og ender i Anus paa Dyrets Rygside. 

 Tarmkanalen er i hele sin Længde fæstet med fine mus- 

 culøse Traade, som tage deres Udspring fra Muskelhuden, 

 til den indvendige Kropsvæg. Tarmen er indvendig be- 

 klædt med Cylinderepithel; nogen egentlig Ciliefure var 

 ikke til at opdage. Omtrent 10 Mm. fra Analaabningen, 

 just hvor Tarmen bliver smalere (Rectum) findes en næ- 

 sten pæreformigj Divertikel af 1 Mm. Længde. Denne 



by 8 rather thick whitish yellow tentacles, which are 

 nearly lancet-shaped, with obtuse extremities and below 

 to some extent lobed. The skin is transparent, firm 

 strongly opalised. The anal aperture is round and on 

 the anterior third part of the body. The layers of muscles 

 are three. The annular muscles (fig. 10 r), the outermost 

 nearest the skin, about 100 in number; the longitudinal 

 museles(figJ0 l),the innermost nearest the perivisceral cavi- 

 ty, 24, and the oblique muscles (fig. 10 s, s), which are situat- 

 ed between both layers. The annular muscle-fascicles, have 

 a width of 0.4 Mm., join very closely together, and pro- 

 perly speaking separate only from each other there, where 

 they are not intersected by the longitudinal muscles. On 

 the glans they go quite into each other. The longitudinal 

 muscles (the fascicles) have a width of 0.3 Mm. and have 

 just behind" the glans a rather large interval, namely 

 0.6 Mm. As they go over into the ridge they join 

 closely together; and, while the exterior fibres of each 

 fascicle cross each other and extend themselves sub- 

 sequently over the glans, the medial fibres run directly 

 back and become more and more rare towards the ex- 

 tremity. The oblique muscles are very small, 0.030 Mm. 

 scarcely more than half as numerous as the longitudinal 

 muscles, and consist of 4—6 fibres. The intervals of the 

 fascicles are 0.12—0.16 Mm. The simple muscular fibres 

 have a thickness of 0.005 Mm. and their sheaths are 

 furnished with rather large nuclei. 



The retractors are 4 which take their origin from 

 the interior surface of the perivisceral cavity, on the 

 anterior portion of its middle third part, as also in 

 pairs somewhat behind the aperture of the rectum; so 

 that two belong to the ventral surface, and two to the 

 dorsal surface. The retractors issue properly speaking 

 from 4 longitudinal muscles with 4 roots, and are at their 

 issue rather wide, becoming a little narrower, but soon 

 recovering their former width, as they go converging 

 towards their place of insertion, the tentacular ring. 



The digestive canal is formed by a very long intestine 

 winding spirally round itself. It begins, at the oral aper- 

 ture, rather narrow, then runs in nearly a straight line 

 back to the height of the anal aperture, increasing some- 

 what in thickness, and makes a slight bend to the middle 

 of the perivisceral cavity, where it forms a loop; it 

 then rises again forward, forms another loop, and then 

 runs out in bends towards the end of the perivisceral 

 cavity. Here it bends itself again forward, looping 

 itself round the part of the intestine that goes in a 

 backward direction, until it comes to the first loop 

 which it goes over; then it runs under the second and 

 foremost loop, becomes now somewhat narrower (rectum 

 fig. 8 re) and terminates in the anus on the dorsal side 

 of the animal. The intestinal canal is in the whole of 

 its length attached by its muscular filaments, which take 

 their issue from the muscular membrane to the interior 

 wall of the body. The intestine is covered in the interior 

 with cylinder-epithelium. No proper ciliary furrow could 

 be discovered. About 10 Mm. from the anal aperture, just 



