137 









denne en Ring med fine spredte Hager. Musculaturen 

 bestaar af to tynde Muskellag, og Kroppens hele indre 

 Flade er stærkt iriserende. 4 Betractorer, der ere tem- 

 melig småle og forene sig i Snabelens forreste Ende, idet 

 de som en Skede omgive Spiserøret (Fig. 42 sp). Bugre- 

 tractorerne tage deres Udspring omtr. fra Kroppens mid- 

 terste Del med en lidt bred Basis, der er omgiven af et 

 tyndt slangeformigt Organ (Fig. 42 o). Rygretractoreme 

 udspringe paa den forreste Del af Kroppen. Spiserøret 

 langt, ledsaget af et contractilt Kar (Fig. 42 k). Tarmen 

 danner 14 — 16 Slyngninger, er forsynet med en Spindel- 

 muskel, der tager sit Udspring lidt foran den korte Ende- 

 tarm og gaar bagover for at fæste sig paa en af de sidste 

 Tarmslynger; forresten har Spiserøret og den første Tarm- 

 slynge en særskilt tendinøs Befæstning. Segm entalorga- 

 nerne temmelig lange og contractile. Nervestrengen som 

 almindelig, Kropshulheden og de deri indeholdte Or- 

 ganer ere beklædte med Peritoneum. 



Farven er varierende fra staalgraa med grønlige Bel- 

 ter til gulbrun, næsten brun med mørkere brune Belter. 



Findested. Bergensfjord 5— -10 Favne, Keferstein; 

 20 — 50 Favne, Koren. Sandig Bund, ikke sjelden. 



Ved den engelske Kyst er den funden først af Mr. 

 Harvey og ved den franske af Grube. 



En af os, Koren, har længe før Keferstein fundet den 

 her beskrevne Art; men antog den allerede dengang for 

 at være Forbes's tidligere beskrevne Syrinx Harven, med 

 hvilken den ogsaa i det Væsentlige stemmer saa ganske 

 overens, at vi ikke have taget i Betænkning at henføre 

 Kefersteins margaritaceum som Synonym med Forbes's 

 Art. Vi have tidligere gjort opmærksom paa, at Sars's 

 Sipunculus margaritaceus er en fra Kefersteins meget 

 forskjellig Art, idet denne, foruden andre Skjelnemærker, 

 ogsaa er forsynet med Hager, hvilket ikke er Tilfældet 

 med hin. Med Hensyn til den Phascolosoma margarita- 

 ceum, som Grube har fundet paa den franske Kyst, og 

 som han henfører til Sars's Art, saa tro vi at kunne 

 oplyse, at denne Art er Kefersteins margaritaceum, (For- 

 bes's Syrinx Harvcii), men ingenlunde Sars's, der efter 

 alt at dømme tilhører de arctiske Have. Grube antager, 

 at Quatrefages's Sipunculus obscurus ikke er andet end 

 Phascolosoma margaritaceum, Keferstein; han har nemlig 

 havt Anledning til at anstille Sammenligning i Pariser- 

 museet. 



FOKKLARING OYER FIGURERNE. 



Tab. 15, Fig 41. Phascolosoma Harveii, naturlig Størrelse. 

 Fig. 42. Samme aabnet. le contractilt Kar; sp Spiserør; o slange- 

 formigt Organ. 



tacular circlet a smooth ring, and below this a ring with 

 fine dispersed hooks. The muscular system consists' of 

 two thin layers of muscles; and the whole interior sur- 

 face of the body is strongly iridescent. 4 retractors, 

 which are rather narrow and unite themselves in the 

 anterior extremity of the proboscis, surrounding the 

 oesophagus like a sheath (fig. 42 sp). The ventral re- 

 tractors take their issue from about the middle part of 

 the body, with a somewhat broad basis, which is sur- 

 rounded by a thin serpentine organ (fig. 42 o). The dorsal 

 retractors issue from the anterior part of the body. The 

 oesophagus long, accompanied by a contractile vessel 

 (fig. 42 k). The intestine forms 14 — 16 circumvolutions; 

 it is provided with a fusiform muscle, which takes its 

 issue a little in front of the short rectum, and goes back- 

 ward, becoming attached to one of the last circumvolu- 

 tions of the intestine. Moreover the oesophagus and the 

 first circumvolution of the intestine have a separate ten- 

 dinous attachment. The segmental organs, rather long 

 and contractile. The nervous cord as usual. The peri- 

 visceral cavity and the organs contained in the same, are 

 covered with the peritoneum. 



The color is various; from steel-grey with greenish 

 belts, to yellowishbrown, nearly brown with darker brown 

 belts. 



Found i the Bergensfjord 5 — 10 fathoms, Keferstein, 

 20—50 fathoms, Koren. On sandy bottom, not rare. 



On the English coast it has been found first by Mr. 

 Harvey, and on the French coast by Grube. 



One of us, Koren, found the species here described 

 long before Keferstein, but took it at that time to be 

 Forbes's previously described Syrinx Harveii, with which 

 in essential points it agrees so entirely, that we have not 

 hesitated to class Keferstein's margaritaceum as syno- 

 nymous with Forbes's species. We have previously noticed 

 that Sars's Sipunculus margaritaceus is a very different 

 species from Keferstein's; the latter being, besides other 

 marks of distinction, furnished with hooks, which is not 

 the case with the former. With respect to the Phas- 

 colosoma margaritaceum, which Grube has found on the 

 French coast, and which he refers to Sars's species, we 

 think that we are able to shew, that it is Keferstein's 

 margaritaceum (Forbes's Syrinx Harveii) but by no means 

 Sars's, which, judging from all things, we must consider 

 as belonging to the arctic seas. Grube supposes that 

 Quatrefage's Sipunculus obscurus is no other than Phas- 

 colosoma margaritaceum Keferst. ; for he has had occasion 

 to institute comparisons in the museum of Paris. 



EXPLANATION OF THE FIGURES. 



Tab. 15, fig. 41. Phascolosoma Harveii, natural size. 

 Fig. 42. The same opened, ft the contractile vessel; sp oesopha- 

 gus; o the serpentine organ. 



