POLYCHAETE WORMS, PART 1 45 



coral, algae. Four specimens were obtained from the oceanographic 

 fouling studies in the New England region (Gulf of Maine). 



Material examined. — Specimens from Labrador, Nova Scotia, 

 New Brunswick, Maine, Alassachusetts, Rhode Island, in low water 

 to 110 fathoms. 



Distribution. — Widely distributed in the Arctic. Also Norway 

 to English Channel, Labrador to Rhode Island, Bering Sea to central 

 California, Yellow Sea, Japan. In low water to 516 fathoms. 



Family Sigalionidae 



Body usually long, narrow, cylindrical, vermiform, with numerous 

 segments. Elytra numerous pau's, borne on loioblike elytrophores, 

 on alternate segments in anterior region (segments 2, 4, 5, 7, etc.) and 

 on all the segments of the posterior region (from segment 23 in Pholoe 

 or segment 27 in Sthenelais, Sigalion, Leanira). Segments bearing 

 no elytra have knoblike dorsal tubercles, without dorsal cirri (except 

 sometimes on third segment). In the bmTOwing forms, which are 

 found buried in mud or sand some centimeters below the surface (e.g., 

 species of Sigalion, Sthenelais, Leanira), all segments except the 

 anterior few have cirriform branchiae, ciliated on the inner border, on 

 lateral sides of the elytrophores and dorsal tubercles hanging down 

 below the elytra. On concave area between branchia and noto- 

 podium is a ciliated area, usually in the form of three cushions or 

 ctenidia provided with long vibratile cilia. The branchiae and 

 ciliated ctenidia thus form a ciliated groove along the laterodorsal parts 

 of the body (fig. 10c). Also in these burrowing forms, the body is 

 prismatic or tetrahedral in cross section, the paired ventral longi- 

 tudinal muscles are well developed, forming a somewhat solelike 

 ventral surface, the dorsal surface slightly arched. 



Parapodia biramous, projecting laterally. Notopodia and neuro- 

 podia equally well developed, the notosetae forming a fanlike spreading 

 bundle and curving dorsally. Notosetae simple, slender, tapering, 

 spinous; neurosetae both simple and compound or all compound. 

 With paired ventral cirri on all segments and a pair of anal cirri. 



Prostomium suboval or subpentagonal, with usually 4 eyes (4, 2, 

 or 0), 1 to 3 antennae, a pair of smooth ventral palps. Parapodial 

 lobes of first or tentacular segment project anteriorly and dorsal to 

 palps, more or less fused to anterior border of prostomium, with or 

 without setae, with 2 pairs tentacular cirri (sometimes, in addition, 

 lateral antennae of prostomium are fused basally to inner sides of 

 tentacular segment). Muscular proboscis evcrsible, with a border 

 of marginal papillae and four interlocking chitinous jaws. Carnivorous. 



