145 



TYLOSOMA, Nobis *; 



SLÆGTSCHARACTEREN. 



Legemet cylindrisk, tæt besat med Papiller. Dets 

 forreste Del afstumpet, bred, skjolddannet, paa hvis Midte 

 en liden fremstaaende, rund Mundaabning. Strax under 

 denne Analaabningen. Dets bagerste Ende eonisk til- 

 spidset. Ingen Snabel, ingen Tentakler, intet Karsystem. 



TYLOSOMA LÜTKEN1I, Nobis. 

 (Tab. 13, Fig. 12, 13 A, B, C. Tab. 14, Fig. 16.) 



Legemet cylindrisk, 15 Mm. langt, 4 Mm. bredt, tæt 

 besat med Papiller, der paa den midterste Del af Krop- 

 pen ere noget fladtrykte og faa under Loupen et skaal- 

 formigt Udseende (Fig. 13 A), medens de saavel mod den 

 forreste bredere, tvers afskaarne Ende, som mod den ba- 

 gerste mere eonisk tilspidsede Del, staa tættere, ere mere 

 fremragende og eonisk tilspidsede. Paa Kroppens ba- 

 gerste Ende en tydelig Grube. Den forreste, bredere 

 Del danner et næsten rundt Skjold, paa hvis Midtparti 

 den lille, runde, fremstaaende Mundaabning sees. Huden 

 er gjennemsigtig, saaledes at den mørke Tarm bliver dun- 

 kelt synbar. Under Mikroskopet vise Papillerne sig at være 

 for en stor Del optagne af de kjertelformige Hudlegemer, 

 der have en yderst kort Udførselskanal. Indenfor Huden 

 findes King- og Længdemuskellaget ordnet paa samme 

 Maade som hos Slægten Phascolosoma i Almindelighed, 

 uden at særskilte Bundter fremstaa. En Retractor, der 

 tager sit Udspring fra den bagerste Ende med to stærke 

 Rødder (Tab. 14, Fig. 16 r, r), der udgjøre næsten Retrac- 

 torens halve Længde, og hvoraf den ene er dobbelt saa 

 bred som den anden. Retractoren gaar omtrent i Midten 

 af Kropshulheden til den forreste Del af Spiserøret. Dette 

 er smalt, langt, følger Retractoren og strækker sig ned 

 til det Sted, hvor dennes tvende Rødder forene sig. Her 

 gaar det over i Tarmen, der löber nu forover og gjør en 

 Bøining, hvorefter den gaar under Retractor (Fig. 16 t) 

 for at komme hen til venstre Side, hvor den danner en 

 Slynge, og gaar saa næsten lodret bag mod det Sted, 

 hvor Spiserøret ender. Her gjør den en Bøining, der 

 ved musculøse Fibre er fæstet til Kropsvæggen, og gaar 

 igjen forover hvor den paany bøier sig for atter horison- 

 talt at strække sig meget langt bagtil (Fig. 16 t). Her 

 gjør den nu en Bøining, hvilken ligeledes ved musculære 

 Fibre er befæstet, idet den slynger sig over begge Re- 

 tractorens Rødder, og kommer saa over til høire Side, 

 hvor den, følgende Retractoren, gaar et Stykke fortil langs 

 denne, og danner nu 3 — 4 spiralförmige Slyngninger 

 (Fig. 16 ts), — gaar atter over Retractorens Rødder til 

 venstre Side, hvor den med flere stærke Fibre er fæstet 

 til Kropsvæggen (Fig. 16 m); herfra gaar den i en meget 

 krum Linie langs Rygfladen som Rectum (Fig, 16 re, re) 



*) TvXoS Vorte, ö&fxa Legeme. 



TYLOSOMA, Nobis-*) 

 GENERIC CHARACTERISTICS. 

 The body cylindrical, densely covered with papillæ. 

 Its anterior part, truncated, broad, scutiform, having in 

 the centre a small prominent, round oral aperture. Imme- 

 diately under this is the anal aperture. Its posterior 

 extremity conically tapered. No proboscis, no tentacles, 

 no vascular system. 



TYLOSOMA LÜTKENI1, Nobis. 

 (Tab. 13, fig. 12, 13 A, B, C. Tab. 14, fig. 16.) 



The body is cylindrical, 15 Mm. long, 4 Mm. broad* 

 densely covered with papillæ, which on the middle part 

 of the body are somewhat flattened, and appear, under 

 the magnifying glass, to be a saucer-shaped appearance 

 (fig. 13 A), while, towards the anterior broader truncated 

 extremity, as well as towards the posterior more conic- 

 ally tapered part, they stand more closely together, are 

 more prominent, and conically pointed. On the posterior 

 extremity of the body an evident hollow. The anterior 

 broader part forms a nearly round shield, the middle 

 part of which appears the small round prominent oral 

 aperture. The skin is transparent, so that the dark in- 

 testine becomes dimly visible. Under the microscope, the 

 papillæ shew themselves to be for a great part occupied by 

 the glandular cuticular bodies, which have an extremely 

 short excretion-canal. Inside of the skin, the annular 

 and longitudinal muscles are found arranged in the 

 same manner as in the genus Phascolosoma generally, 

 without separate fascicles being produced. One re- 

 tractor, which takes its issue from the posterior extre- 

 mity, with two strong roots (Tab. 14, fig. 16 r, r), that 

 form nearly half the length of the retractor, and of which 

 one is twice as broad as the other. The retractor goes 

 about in the middle of the perivisceral cavity to the 

 anterior part of the oesophagus. The latter is narrow 

 and long, accompanies the retractor and extends down 

 to that place where the two roots of the retractor unite. 

 Here it goes over into the intestine, which now runs 

 forward and makes a bend, after which it goes under 

 the retractor (fig. 16 t), coming to the left side, where 

 it forms a circumvolution, and then goes nearly per- 

 pendicularly backward towards the place where the oeso- 

 phagus terminates. Here it makes a bend, which is 

 attached to the wall of the body by muscular fibres, 

 and goes again forward, where it bends once more so 

 as to extend itself again horisontally very far backward 

 (fig 16 t). Here it makes another bend, which in 

 like manner is attached by muscular fibres, twining 

 itself over both the roots of the retractor, and so coming 

 over to the right side, where, accompanying the retractor, 

 it goes some distance forward along the latter, and forms. 



*) TvÅoS, wort; oæfxa^ body. 



