30 AUGUSTA ÄRNBÄCK-CHRISTIE-LINDE, NORTHERN AND ARCTIC INVERTEBRATES. 



Cnemidocarpa rhizopus Redikorzew 1907. 



Pl. 1, figs. 18—20. Pl. 2, fig. 22. Text-fig. 3. 



Syu. Styéla rhizopus, Redikorzew 1907, 1910. 

 Tethyum rhizopus, Hartmeyek 1909. 



Habitat. 



Galtegat: Kummelbanken, 3 sps (1900, T. Tullberg). 



East Greenland: Greenland Exp. 1899: S. of the Pendulum Island, 74° 35' 

 N-18° 23' W, 18—21 m, mud with sand and algae, 3 sps (July 6, 1899); S. E. of 

 the Clavering Island, 74° 10' N — 20° 8' W, 25—40 m, mud with shells and stones, 

 3 sps (July 17, 1899). 



West Spitzbergen: Spb. Exp. 1861 (I. A. Malmgren): Hakluyts Headland, 

 12—30 fms, stones and algae, 1 sp (May 1861); Danes Gat, 20 fms, sand and stones, 

 many sps; Treurenburg Bay, 20 fms, 2 sps; Waigat Islands, 60 fms, clay, 3 sps 

 (August 1861). — Spb. Exp. 1864 (I. A. Malmgren): Stor Fjord, 5—20 fms, clay 

 and stones, 1 sp (August 23, 1864). — Bel Sound, 5—20 fms, clay or clay with 

 stones, many sps. — Spb. Exp. 1868 (A. I. Malmgren): Lovén's Mount, 36 fms, 

 clay with stones, 2 sps (September 11, 1868). — Spb. Exp. 1872—1873: Mossel Bay, 

 8 — 15 fms, various bottoms: sand, clay with algae, especially Lithothamnion, 

 many sps. 



Novaja Zemlja: N. Zemlja Exp. 1875: Waigatch Island, Cape Grebeni, 8—10 

 fms, clay or clay with sand, a great number of specimens (July 25 — 31, 1875, Théel 

 a. Stuxberg). 



General Distribution. 



The species has been reported from the Arctic Sea of Siberia, W. of West 

 Taimyr; depth, 9 m; bottom, mud and sand (ef. Redikorzew 1910). 



Remarks. 



To the description given by Redikorzew the following notes should be added. 



As is shown from figs. 18 — 20, the body is of various form, it is generally 

 cylindrical with a tapering posterior part, or conical with a bulb-shaped base ; some- 

 times it is almost spherical. The anterior end, where the apertures are placed, is 

 somewhat flattened. The apertures are near together and easily distinguished; they 

 are surrounded by circular folds of the test. The test is thin and incrusted with 

 very fine sand grains. From its ventral side numerous rhizoid-like processes arise. 

 The atrial tentacles are arranged in a single row. The dorsal tubercle is almost 

 circular, its opening is directed to the left. According to Redikorzew (1910) the 

 opening is turned to the right, a statement which probably is due to a mistake, 

 since such an arrangement has been observed in no specimen among the numerous 

 collection here examined. 



