POLYCHAETE WORMS, PART 1 27 



Biology. — Found living commensally in the intertidal burrows 

 of Nereis virens Sars in the sandy mud (Newcastle, New Hampshire; 

 Boothbay Harbor region, Maine). Small and rather fast moving, 

 easily escapes notice. Found sharing the tube of the maldanid 

 Praxillella gracilis (Sars) (Sheepscot River, Maine, 5 fathoms, 1955, 

 R. W. Hanks). Dredged on bottoms of mud, fine sand, silty clay, and 

 muddy sand in 3 to 90 fathoms. Females found filled with eggs in 

 November (Newcastle, New Hampshire, 1954, G. M. Moore). 



Material examined. — Specimens from Maine (Sheepscot estuary, 

 Boothbay Harbor region). New Hampshire (Little Harbor, New- 

 castle), Massachusetts (Georges Bank, Cape Cod), in low water to 90 

 fathoms. 



Distribution. — Maine (Boothbay Harbor region) to Massachusetts 

 (Cape Cod). Low water to 90 fathoms. 



Genus Arcteobia Annenkova, 1937 



Type (original designation): Arcteobia anticostiensis (Mcintosh, 

 1874). Contains only one New England species. 



Arcteobia anticostiensis (Mcintosh 1874). 



Figure G,j,k 



Eupolynoe anticostiensis Mcintosh, 1874, p. 265, pi. 10, figs. 1-4. — Whiteaves, 



1901, p. 85. 

 Eucranta anticostiensis Treadwell, 1948, p. 16, fig. 56. 

 Arcteobia anticostiensis Pettibone, 1954, p. 225; 1956a, p. 551. — Uschakov, 1955, 



p. 146, fig. 32. 



Description. — Length up to 26 mm., width including setae up to 

 8 mm., segments up to 36. Prostomium with distinct cephalic peaks; 

 anterior pair of eyes antero ventral. Elytra 15 pairs, cover the 

 dorsum, without fringes of papillae, smooth except for scattered 

 microtubercles on anterior curved part. Upper notosetae shorter, 

 stouter, with blunt tips; rest of notosetae with capillary tips. Few 

 upper neurosetae longer, ending in sharp slender tips; rest of neuro- 

 setae with bifid tips. Color: irregularly banded middorsally, greenish 

 to greenish black; elytra with reddish brown pigmented areas. 



Biology. — Dredged on bottoms of sandy mud and mud with 

 various combinations of sand, pebbles, gravel, stones, rocks, and 

 shells. Probably commensal in habit. Found living commensally 

 in the sinuous tubes of the terebellid Pista Jlexuosa (Grube), one 

 worm per tube (off Labrador, Pettibone, 1954). Found in the tubes 

 of a maldanid (Gaspe Bay, 10-23 fathoms, June 1957, August 1958; 

 Georges Bank, 42°51' N., 70°36' W., 51 fathoms, July 1960). 



Material examined. — Off Labrador, Gaspe Bay and Bay of 

 Chaleurs in Gulf of St. Lawrence, Nova Scotia, Maine, Massachusetts, 

 in 3 to 95 fathoms. 



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