KUNGL. SV: VET. AKADEMIENS HANDLINGAR. BAND 39. N:o l. 63 
ferent conditions of preservation. All the specimens of "Forma sibirica"" are charac- 
terised by a thin, almost transparent, body-wall, with hardly discernible reticulation 
and, on the whole, by a more delicate development of the internal organs. The ten- 
tacles, which seem to be somewhat more obtuse and less numerous than in the westerly 
form, vary considerably in number, as may be gathered from the subjoined table. 
| Number of the Length of the Diameter of 
»Forma sibirvica» Localities 
tentacles body. the body 
I | FSS 
16 35 mm. | 3 mm. | Konyam Bay- 
26 | 45 ium. | 4,5 mm. 75? n.—113? 30! e 
22 | 47 mm. | 3,95 mm. | Konyvam Bay. 
25 50 min. | 3,5 mm. | » 
30 52 mm. | 5 mm. | 75? n.—113” 30' e. 
24 | 58 mm. | 6 mm. | » 
33 60 mm. 6 mm. | Konyam Bay. 
TT | 60 mm. | 6,5 mm. | » 
39 62 mm. | 7 mm. 75” n.—113” 30! e. 
60 91 mm. | 10,5 mm. | Konyan Bay. 
General Distribution. 
Phascolosoma margaritaceum is a true arctic form and, possibly, it may also 
have a circumpolar distribution. Besides the above-enumerated localities KOREN and 
DANTIELSSEN mention that they have found it at Lofoten, Tromsö, Komagfjord, 
Hammerfest, all places within, or in the closest vicinity to the Arctic Sea. MSupposing 
the identification to be right, a single specimen is found as far southward as in Sogne- 
fjord, 61” 10' n.—6” 32 e., at a depth of 1229 m. (KoREN and DANIELSSEN 1881). 
As a rule, the species in question do not frequent the deepest parts of the ocean; 
on the contrary it lives in comparatively shallow water. 
Phascolosoma Hanseni (DANIELSSEN and KOREN 1881), SELENKA 1883. 
PI VACfgst 38435 PI XIvVE fig: 19 
Stephanostoma Hanseni DANIELSSEN and KOREN 1881. 
33 Barentsu Horst" 1882 (?). 
SELENKA is right in eliminating the genus Stephanostoma, and in ranging it 
among the synonyms. There exists in reality not a single character that would justify 
its being kept apart from the old genus, Phascolosoma. Besides, I am convinced of 
its close relation to Phascolosoma margaritaceum of SARS, to such a degree indeed, 
that I am scarcely able to distinguish them, the one from the other. Nevertheless, 
they may be looked on as separate until more materials for comparison have been 
obtained. I have only myself had the opportunity of examining two fragmentary 
specimens of the types of DANIELSSEN and KOREN. 
t Niederländ, Archiv fir Zoologi, Supplementband I, 3, 1882, 
