26 THÉEL, PRIAPULIDS AND SIPUNCULIDS OF THE SWED1SH ANTARCTIC EXPEDITION 1901 — 1903. 



The thin body-wall is strengthened by circular and longitudinal muscles. The 

 former constitute a continuous layer all över the body on the outside of the latter, 

 which present a somewhat different disposition (fig. 17). In the trnnk they form a 

 continuous layer, except posteriorly, where the longitudinal fibres are separated into 

 bands which converge and terminate round the margin of the muscular diaphragmatic 

 membrane. They probably function as a kind of retractors. In the intro vert, on 

 the other hand, all the longitudinal muscular fibres are separated into distinct bands. 



With regard to the true retractors, I counted eight long ones, two of which 

 run out from the body-wall in front of the remaining ones, which originate from the 

 middle of the trunk. Concerning the short retractors of the intro vert, they exist, 

 though I have not been able to state their number. 



Phascolosoma margaritaceum (Sars)(?). 



Pl. II, fig. 20 and Pl. V, figs. G7 and 68. 



1851. Slpuncuhis margaritaceus Särs. 1 



1868. Pliascolosoma capsiforme Baird. 2 



1889. » antarcticum Michaelsen. 3 



1889. » fuscam Michaelsen. 3 



1889. » georgianum Michaelsen. 3 



1896. » margaritaceum (Särs) var. capsiforme Baird. Fischer. 4 



Habitat. — Falkland Islands: Port Louis, Mouth of Carenage Creek, 3—4 

 m., shells and stones, Va 1902. Three large specimens of a dirty brown colour. — 

 Port Louis, the shore, 30 /i 1902. Four whitish specimens of ordinary size. — Port 

 Louis, Greenpatch, 7 m., mud and gravel, 28 /7 1902. One ordinary specimen. — Port 

 Albemarle, 15 m., sand and algse. 8 /o 1902. One specimen. — Port Albemarle, 18—30 

 m., sand, n /9 1902. Three small specimens. — West Point Island (Sw. Mag. Exp. 

 B /i2 1907). — Port William, 17 m., sand, 3 /<> 1902. Two brown specimens. — Stanley 

 Harbour, 10 m., mud and shells, 3 h 1902. Sixteen small specimens. — South Ge- 

 orgia: Cumberland Bay: »Grytviken», 22 m., clay and algse, 30 /s 1902. Several 

 small specimens. — »Majviken», 75 m., clay and algae, 14 /5 1902. Many small speci- 

 mens. — »Sydfjord», 195 m., clay and stones, 29 /r> 1902. Many small specimens. — 

 Tierra del Fuego: Punta Arenas, Tribune Bank, Puerto Eugenia, Gente Grande, 

 Puerto Harris. From all these localities a number of specimens have been brought 

 home by the Swedish Expedition 1895—96. — Graham Region: 64° 20' S.— 56° 38' 

 W., 150 m., sand and gravel; 16 A 1902. Six specimens. — 65° 56' S.— 54° 35' W., 

 920 m., mud and stones; 22 /i 1902. One very minute specimen. — SW of Snow Hill 

 Island, 125 m., clay and stones, 21 /i 1902. One specimen. 



1 Beretning om en i Sommeren 1849 foretagen zoologisk Reisc i Lofoten og Finmarken. — Nyt Mag. f. 

 Naturvidenskaberne. VI. Christiania 1851, p. 196. 



- Proceed. Zool. Soc. London 1868, p. 83, pl. IX, fig. 3. 



:f Jahrbuch der Hamburgischen Wissenschaftlichen Anstalten. VI. Hamburg 1889, p. 3, figs. 4 a— c. 



1 Gephyreen. Ilaniburger Magalhaensische Sannnelreise. I. Hamburg 1896, p. 3. 



