KUNGL SV. VET. AKADEMIENS HANDLINGAR. BAND 63. N:0 2. 37 



seem to be less rudimentary and the longitudinal vessels of the folds are more nu- 

 merous in the form from the Bering Sea, but, as has been pointed out above, the 

 number of the vessels is not constant in C. rhizopus. 



The rhizopus group is of wide distribution in the Arctic region and the eastern 

 and western Boreoarctic mixture zones, and its range even extends into the Boreal 

 region comprising, eastward, the North Sea waters and, westward on the American 

 Atlantic coast, the Long Island Sound. In the Arctic region species of this group 

 are found from the Arctic N. America in the west to the Arctic Sea of Siberia in 

 the east, or, if Styela sabulifera from the Bering Sea is included, it is circumpolar. 



The different species are distributed as follows: C. rhizopus occurs abundantly 

 off Novaja Zemlja and is also reported from the Arctic Sea of Siberia, West Spitz- 

 bergen, East Greenland, the Murman coast and Cattegat, where it has been dredged 

 once and in only three specimens. This species has not been reported from West 

 Greenland, where the group is represented by C. cirrata of which a few individuals 

 ha ve been collected also off East Greenland, West Spitzbergen and the Arctic North 

 America. On the east coast of N. America the species C. mollis and C. mortenseni 

 occur. The former has been dredged from the Gulf of St. Lawrence to Long Island 

 Sound and, moreover, off the British coast: Northumberland and Durham, Styela 

 vestita having proved to be an identical form. Of the latter, i. e. C. mortenseni, 

 only four specimens have yet been collected, viz. three specimens from the east 

 coast of N. America 42° 30' 15" N— 70° 38' W and 44° 26' N— 62° 10' W, and one 

 specimen from Skagerrack 58° 6' N — 9° E (»Norska rännan»). Of C. mollispina a 

 single specimen is known from the Kola Peninsula. 



Polycarpa libera Kiaer 1893. 



PI. 2, fig. 33. 



Syn. Glandulu (ubularis, M. Saks 1858. 

 Polycarpa comata, Bonnevie 1896. 

 Pandocia libera, Hartmeyek 1909. 



Habitat: 



West coast of Sweden: Bohuslän, Gullmarn (July- August, 1918 — 1919, Ärnbäck): 

 Spättan, 30 m, 7 sps, bottom, clay; Smedjan-Flatholmen, 30 — 40 m, many sps; 

 Smedjan, 8 sps. — Sörgrundsberget, S. W. of Hållö, depth, about 10 m, 3 sps 

 (August 1, 1913). — N. of Vinga fyr, 16—42 m, 2 sps (August 1, 1906, T. Lager- 

 berg). — Styrsö, 20 fms, 1 sp (July 6, 1869, Olsson). — Väderöarna, 10 fms, sand 

 and rocks, 1 sp (1862). — W. of Nord-Koster, 12 — 18 fms, rocks, 1 sp (August 4, 

 1865). — Kosterrännan, E. of Ramsholmen clay, depth, about 100 fms, 1 sp (July 

 24, 1919, M. Aurivillius). 



Cattegat: Kummelbanken, 1 sp. (1900, T. Tullberg), 



East Greenland: Off Murray's Island, 71° 33' N— 21° 30' W, 200 m, mud and 

 sand, 1 sp (July 28, 1899, Greenland Exp. 1899). 



