10 THÉEL, NORTHERN AND ARCTIC INVERTEBRATES. I. SIPUNCULIDS. 
1. Chitinous inerusted shields at anus and at the posterior 
extremity of the body missing . . . . . . . . . Phascolosoma. 
2: Chitinous shields present fbe orsa 5 . Åspidosiphon. 
II. Intestinal tube does not form a spiral, but sd a fv got 
fixed by musecular fibres to the body-wall. One segmental 
organ fixed by muscular. threads. Retractors 1 to 3; our 
northern forms have 1 dorsal and 2 ventral, the latter joined 
together, except at the bases which embrace the nerve-cord. Phascolion. 
b. Anus removed forward from the trunk to the proboscis, more 
or less in the neighbourhood of the mouth. One retractor 
attached to the posterior end of the trunk. One segmental 
organ. Oesophagus forms a few coils and passes into a short, 
somewhat, irregular, SPpiralti ou er sr OM GCIUINeSOTMOR 
Physcosoma Selenka 1897'. Besides having the characters already mentioned in 
the Synopsis, the genus is marked by possessing numerous papille in the skin, in the 
majority of cases annular series of hooks, four rarely three or two retractors, two segmental 
organs, one contractile vessel and eye-spots. A divertiele at the rectum is wanting. 
The alimentary canal is coiled to a true spire with spindle-musele, which in most 
cases is attached posteriorly as well as anteriorly. 
Only a single species of this genus is hitherto known from our northern seas. 
Its discoverers, KOREN and DANIELSSEN 1875 and 1877, and later LEVINSEN”, have 
wrongly referred it to the genus Phascolosoma, far different from it in many respects. 
SELENKA was the first to understand the true nature of this animal. The two Nor- 
wegian investigators overlooked the presence of annular series of hooks, the conse- 
quence of which was that later investigators, including SELENKA and SHIPLEY” 1891, 
wrongly referred it to that small group of Phymosoma-forms which is without hooks. 
Svpuwnculus LINNÉ" 1766. Besides referring to the Synopsis, we may note the 
following Derss True papille absent. Four retractor-museles. Two segmental organs. 
1 In his NE of 1883 and 1885 SELENKA revived the name Phymosoma given by QUATREFAGES in 
18635 (Hist. nat. des Annelés marins et d'eau douce). Being latér informed of the fact that this name was 
already appropriated in zoological literature for other purposes, he proposed to exchange it for »Physcosoma» 
(Zool. Anzeiger XX. 1897, p. 460). Next year, SPENGEL, in his turn, made the proposal to change the name 
altogether, in order to avoid confusion (Zool. Anzeiger XXI. 1898, p. 50). For my part, I consider it more 
suitable to keep the name given by SELENKA. 
In 1900 LAmBERT (Bull. Soc. Sc. de I'Yonne. Vol. 53) writes in a footnote to his »Étude sur quel- 
ques Echinides de I'Infra-Lias et du Lias»: »Le nom de Phymosoma SHIrEY, récemment proposé pour des 
Holothuries, devra étre abandonné et je propose de le remplacer par Prophymosoma.» (Sie!) Can it be pos- 
sible that the author of this note has made the great blunders of confounding Holothurids with Sipunculids, 
of confusing the well-known investigator SHIPLEY with SHiPEY [an author unknown to mel, and, finally, of 
imagining that SHIPLEY was the creator of the genus name Phymosoma? HLately I have found that my suspi- 
cions have been confirmed by BATHER (Zool. Record. Echinoderma. XXXIII. 1900, pp. 77—798), who, in 
his turn, proposes the name Physconosoma. 
Vidensk. Meddel. fra den naturh. Foren. i Kjöbenhavn. 1882 and 1883. 
Quart. Journ. of Microsc. Science. Vol. XXXII. 1891. 
Systema nat, Ed. XII. 1766, 
Fr w NS 
