POLYCHAETE WORMS — PETTIBONE 567 



New records: Labrador: Strait of Belle Isle, 15-20 fms., sand; 

 2 specimens, Station 15. West Coast North America: Wasliington 

 Sound, low water, M. H. Pettibone; Chichagof Harbor, Attn Island, 

 gravel and mud, 1873, and Cliiachi Islands, Alaska, 20 fms., mud, 

 1874, W. II. Dall; Karluk, Alaska, Alaska Salmon Investigation, 1903. 



Distribution: Widely distributed in the Arctic: Siberian, Alaskan, 

 and Canadian Arctic, Davis Strait, Greenland, Jan Mayen, Spits- 

 bergen, Novaya Zemlya, Kara Sea. Also Iceland, Faroes, Norway 

 (o France; Labrador to Maine; South Africa; Bering Sea to Wash- 

 ington Sound; north Japan Sea. In low water to 1,501 fathoms. 



Genus Ophelia Savigny, 1822 



Ophelia Umacina (Uathke, 1843) 



Ammolrypane Umacina Rathke, 184:?, pp. 190, 202, pi. 10, figs. 4-8. 



Ophelia Umacina Verrill, 1881, pp. 289, 316, 319.— Not Webster and Benedict, 

 1884, p. 724 (-=0. hicornts) .—Fauvel, 1927, p. 132, fig. 46,i-l.— Treadwell, 

 1937, p. 32.— Annenkova, 1937, p. 177; 1938, p. 187.— Hartman, 1938, 

 p. 107, figs. 55-58; not 19421), p. 130 ( — 0. denUculata). — Berkeley and 

 Berkeley, 1943, p. 130.— St0p-Bowitz, 1946b, p. 32, fig. 2; 1948b, p. 12, 

 fig. 3.— Zatsepin, 1948, p. 137, pi. 33, fig. 5.— Wesenberg-Lund, 1950a, p. 37; 

 1950b, p. 88; 1951, p. 83.— Tebble, 1952, p. 561, fig. 4; 1953, pp. 362, 365. 



OpheUa boreaUs Tebble, 1952, p. 553, figs. 1-3; 1953, pp. 362, 365.— Berkeley and 

 Berkeley, 1954, p. 467. 



OpheUa assimiUs Tebble, 1953, p. 367. 



Description: The two specimens from Labrador are 29-33 mm. 

 long, 3.5-4 mm. wide, consisting of 33 setigerous segments: 10 pre- 

 branchial, 16 branchial, and 7 postbranchial. Ventral groove begins 

 on setiger 7. The dorsolateral circlet of anal papillae are rather 

 long, the setae of the posterior segments are long, extending well 

 beyond the posterior end of the body. The paired dorsolateral 

 longitudinal ridges on the posterior five segments (setigers 29-33) 

 are prominent. 



Remarks: Tebble (1952) has attempted to distinguish between 

 Ophelia borealis Quatrefages (10 prebranchial setigers, typically 

 20 (16-20) branchial setigers, 6 (6-10) postbranchial setigers, 36 

 (34-36) total number of setigers, with dorsolateral circlet of anal 

 papillae long and thin, and with setae of posterior segments long, 

 concealing the anal segment) and 0. Umacina (10 prebranchial 

 setigers, typically 22 (18-23) branchial setigers, 7 (6-10) postbranchial 

 setigers, 39 (38-39) total number of setigers, with dorsolateral circlet 

 of anal papillae short and blunt, and setae of posterior segments 

 short). In the material examined by Tebble, the two groups could 

 be separated and there were no intergi'adations. However in the 

 material examined in the U. S. National Museum from Greenland, 

 Canadian Arctic, Arctic Alaska, Labrador, Washington, Oregon, and 

 central California there were all gradations from the typical 0. 



