126 



----- £ 



Pig» 9. Et Stykke Hud af en ung Sipunculus norvegicus, 800 

 Gange forstørret (Osmiumsyre-Præparat, farvet med 

 Hæmatoxylin). pn primær Gren fra Bugstrengen ; r Ring- 

 muskler; a Nervetraade tabende sig i Cuticularepithe- 

 let; b <& c Hudlegemer med deres Nerver; e Muskelkjer- 

 ner; é Muskelkjerne med tilsyneladende Nerve-Ende; 

 f,f den sædvanlige Maade for Nervetraadens Udbredning 

 i Musklerne; g Nerveganglier; h Epithelceller ; nt Nerve- 

 traade. 



Fig, 10. Hudstykke af Sipunculus norvegicus, seet indenfra, stærkt 

 forstørret. I Længdemuskler; r Ringmuskler; s, s, s Skraa- 

 muskler; p, p Parietal-Peritoneum ; le, Je Kar; i, i, i Ind- 

 gangsaabninger til Karrene. 



SIPUNCULUS PBIAPULOIDES, Nobis. 

 (Tab. 13, Fig. 1—6.) 



Kroppen cylindrisk, 115 Mm. lang, 55 Mm. i Om- 

 kreds, forsynet med 24 stærke Længderibber, der dog 

 ophøre ved den bagerste Del (Fig. 1 Ir), som gaar over 

 i Glans. Denne, der er 30 Mm. lang, glat og ligner fuld- 

 stændig Glans paa det mandlige Membrum, danner for- 

 oven en temmelig stor, fritstaaende Vold, egentlig Hud- 

 fold, som omgiver hele Eyggen og Sidepartiet til henimod 

 Bugfladen, hvor den paa hver Side forlænger sig conver- 

 gerende bagtil omtr. 4 Mm. fra den afrundede Ende, 

 hvorved fremkommer paa denne Del af Glans en Fure, 

 der er bredest fortil. Voldens øverste Band har et 

 crenuleret Udseende, imedens dens Bugrande ere glatte. 

 — Paa den afrundede Ende af Glans sees en liden 

 rundagtig Fordybning, som under Sammentrækningerne 

 antager forskjellige Former og faar stundomen skuf- 

 ende Lighed med en Aabning (Porus), hvoraf der dog 

 ingen gives. Ved denne Fordybning fremkommer lige- 

 som to Læber (Fig. 2 1), af hvilke den, der svarer til 

 Rygsiden (Fig. 1 1), er mest fremragende ; forøvrigt kau 

 Glans trække sig stærkt sammen, og da antager den de 

 forunderligste Former, men beholder altid sin Vold. Sna- 

 belen er omtrent V 3 saa lang som hele Dyret, forsynet 

 med store, fremragende coniske Papiller, der danne Længde- 

 rækker og blive mindre imod Mundaabningen. Tentakel- 

 membranen danner 12 Flige, hvoraf to meget lange, en 

 paa Ryg- og en paa Bugsiden; de øvrige ere kortere, 

 men alle ere i Randen mere og mindre indskaarne. Anal- 

 aabningen, der findes 22 Mm. fra Legemets forreste Ende, 

 er aflang paatværs, stærk foldet, men bliver fuldkommen 

 rund under Udførsel af Excrementer. Huden halvgjennem- 

 skinnende, aflang, gittret paa den egentlige Krop, imedens 

 der paa Glans intet Gitter findes. Muskellagene ere trende ; 

 Ringmusklerne findes paa Kroppen fra Snabelens Begyn- 

 delse og til Glans i adskilte Bundter, der ved at over- 

 skjære Længdemusklerne danne Hudgitteret; men paa 

 Snabelen og Glans lægge Bundterne sig sammen, saa de 

 næsten danne en sammenhængende Muskelhud. Længde- 

 musklerne ere 24, og træde frem i stærke Bundter, der 

 ere fuldkommen adskilte over hele Legemet. Paa Sna- 

 belen slutter dog det ene Bundt sig til det andet; paa 



Fig. 9. 



Fig. 10. 



A piece of the skin of a young Sipunculus norvegicus^ 

 magnified 800 times. Osmium preparation colored with 

 Hæmatoxyline. pn primary branches from the ventral 

 cord; r annular muscles; a nervous filaments losing 

 themselves in the cuticular epithelium ; b & c cuticular 

 corpuscles with their nerves; é muscular nuclei with ex- 

 tremities of corresponding nerves; f,f the usual manner 

 in which the nervous filaments are distributed in the 

 muscles; g the nervous ganglions; h epithelial cells« 

 nt nervous filaments. 



Piece of the skin of Sipunculus norvegicus viewed from* 

 the inside, strongly magnified. I longitudinal muscles- 

 r annular muscles; s, s, s oblique muscles; p,p parietal 

 peritoneum; Jc, k vessels; i, i t i entrance apertures to 

 the vessels. 



SIPUNCULUS PBIAPULOIDES, Nobis. 

 (Tab. 13, fig. 1-6.) 



The body cylindrical, 115 Mm. long, 55 Mm. in cir- 

 cumference, with 24 strong longitudinal ribs, which however 

 terminate at the posterior part (fig. 1 lr) that goes over 

 to the glans. The latter, which is SO Mm. long, smooth 

 and perfectly like the glans of the virile member, forms 

 above a rather large, freely standing prominence; pro- 

 perly a fold in the skin surrounding the whole back and 

 the side part, until near the ventral surface, where it is 

 elongated on each side, converging backward with about 

 4 Mm. on the round end, whereby there is produced, 

 on this part of the glans, a furrow which is widest" 

 in front. The superior margin of the prominence 

 has an crenulated appearance, while the ventral margins 

 are smooth. On the rounded end of the glans there ap- 

 pears a little roundish cavity, which during the contrac- 

 tions assumes various forms, and acquires sometimes a 

 deceptive resemblance to an aperture (porus), which 

 however does not exist. By this hollow, there are pro- 

 duced, as it were, two lips (fig. 2 1) of which one, corre- 

 sponding to the dorsal side (fig. 1 1), projects most; 

 moreover the glans can be strongly contracted; and 

 then it assumes the most remarkable forms, always re- 

 taining, however, its annular prominence. The proboscis 

 is about V 3 as long as the whole animal, furnished with 

 large prominent conical papillæ, which form longitudinal 

 rows and become smaller towards the oral aperture. 

 The tentacular membrane forms 12 lobes, of which 2 are 

 very long, one on the dorsal side, and one on the ventral 

 side; the others are shorter; but all are more or less 

 cut out at the edge. The anal aperture is 22 Mm. from 

 the anterior extremity of the body; it is oblong transver- 

 sely, strongly folded, but becomes perfectly round during 

 the ejection of excrements. The skin is semi-transparent, 

 oblong-latticed on the proper body; while on the glans 

 there are no lattices. The layers of muscles are three; 

 the annular muscles are found on the body, from the 

 beginning of the proboscis to the glans, in separate fas- 

 cicles, which, by intersecting the longitudinal muscles, 

 form the cuticular-lattice. On the proboscis and on the 

 glans, the fascicles lie close together, so as to form> 







