KUNGL. SV. VET. AKADEMIENS HANDLINGAR. HAND 47. N:<> I. 27 



The collections of Phascolosoma margaritaceum are comprehensive euougfa ;in<l 

 contain forms of all dimensions, ranging from samples of a few millimeters fco giant 

 specimens measuring 125 mm. or more in longth. The largesl specimens have been 

 brought home from Port Louise in the Falkland Islands, and among them some indi- 

 viduals have a whitish-gray colour, while other specimens are dirty brown with fche 

 posterior pointed end slightly darker. Two forms from Port William in the Falkland 

 Islands are dark brown. These differences in colouring are not of any consequence 

 for the relationship of the forms in question. 



Some years ago I had the opportunity of examining the very rich collections 

 of arctic Phascolosoma-specimens which are kept in the Swedish State Museum, 1 and 

 which also contain samples of all dimensions. Consequently I have had an excellent 

 opportunity for drawing comparisons between the specimens of the two cold seas. 

 Nevertheless, all my endeavours to exhibit true differences between them were fruitless. 



Even the young specimens of the two cold seas resemble one another very 

 closely. In both of them the number of the tentacles is much diminished, and the 

 papilke of the body-wall are comparatively more prominent than in older specimens. 

 In the antarctic small forms those papillae seem often to have a darker colour. 



The sample which is rendered on plate II has a length of about 69 mm., is 

 provided with 60 tentacles (fig. 67) and is in possession of ciliated sense-pads common 

 to most of the Sipunculids. The inner organisation of the two antipods is quite the 

 same (fig. 68). 



In 1889 Michaelsen 2 examined samples of this species from South Georgia and 

 described them under the name of Phascolosoma antarcticum n. sp. But, to judge 

 from the following quotations, he was in doubt whether he was right in refering them 

 to a new species. For he says: »Ph. antarcticum steht dem Ph. margaritaceum Särs 

 auffallend nahe; es war urspriinglich sogar meine Absicht, diese Tiere unter dem 

 Namen Ph. margaritaceum Särs var. antarcticum zu beschreiben. Die Untersuchung 

 der iibrigen Phascolosomen von Siid-Georgien liess mich meine Ansicht ändern. » 

 Further on he continues: »Ich beschreibe deshalb sowohl Ph. juscum wie auch Ph. 

 antarcticum als gesonderte Arten, mit dem Hinweis, dass sie wahrscheinlich als Unter- 

 arten des Ph. margaritaceum auzusehen sind, ebenso wie Ph. capsijorme Baird und 

 Ph. papillosum Thomps.» 



Låter on in 1896 Fischer 3 submitted the matter to a renewed discussion and 

 sets forth his view as follows: »Ich vereine desshalb dieser Form [Ph. capsijorme] 

 nebst den sudgeorgischen Phascolosomen (Ph. antarcticum Mich., Ph. juscum Mich. 

 und Ph. georgianum Mich.) mit den nordischen Ph. margaritaceum Särs zu einer Art.» 



Considering that I have in vain sought for differences of such significance as 

 to admit the maintenance of the above-mentioned species, I quite agree with Fischer 

 in regarding them as representatives of our northern Ph. margaritaceum. Moreover, 

 I think it appropriate to reject the varieties too. 



1 Kungl. Svenska Vetenskapsakademiens Handlingar. Bd. 39. 1905. 

 s Op. cit. 

 3 Op. cit. 



