POLYCHAETE WORMS, PART 1 215 



(Parris Island), Florida (Seahorse Key, off Tampa), Washington 

 (Puget Sound), low water to 45 fathoms. 



Distribution. — Massachusetts (Buzzards Bay and Vineyard 

 Sound) to Florida, Gulf of Mexico, south to Brazil and Argentina; 

 western Canada (Vancouver Island) to Lower California, Mexico, 

 south to Peru; Straits of Magellan, New Zealand, South Australia. 

 Low water to 172 fathoms; sexual forms in surface waters. 



Glycera dibranchiata Ehlers, 1868 



Figure 55 



Glycera dibranchiata Ehlers, 1868, p. 670, pi. 24, figs. 1, 3-8, 10-28.— Not Tread- 

 well, 1924, p. 14 ( — G. sphyrabrancha Schmarda). — Treadwell, in Cowles, 

 1930, p. 344.— Procter, 1933, p. 140.— Hartman, 1944a, p. 339, pi. 18, fig. 1; 

 1945, p. 23; 1950, p. 70, pi. 10, figs. 9, 10; 1951, p. 50.— Gustafson, 1953, p. 7.— 

 MacPhail, 1954, p. 11, fig. 3.— Dow and Wallace, 1955, p. 1.— Renaud, 1956, 

 p. 19, fig. 15.— Klawe and Dickie, 1957, p. 1, figs. 1-18.— Rioja, 1958, p. 258.— 

 Stickney, 1959, p. 17. 



Rhynchobolus dibranchiatus Verrill and Smith, 1874, pp. 38, 47, 70, 77, 83, 134, 

 137, 140, 169, 302, pi. 10, figs. 43-44.— Webster, 1879, p. 245; 1886, p. 146. 



Euglycera dibranchiata Verrill, 1881, pp. 296, 301, 304, 308, 322.— Webster and 

 Benedict, 1884, p. 723; 1887, p. 726.— Sumner, Osburn, and Cole, 1913, p. 

 623.— Andrews, 1891a, p. 288. 



Description. — Length up to 370 mm., width up to 11 mm., seg- 

 ments up to 300. Parapodia (fig. 55,c,f,g) with 2 sharply conical 

 presetal lobes throughout the length of the body. Two shorter, 

 bluntly conical postsetal lobes in the anterior region, the upper one 

 being shorter, rounded and the lower one longer, bluntly conical; in 

 the middle region the 2 postsetal lobes are both bluntly conical, the 

 upper one shorter than the lower one. In the posterior parapodia, 

 there may be a single rounded postsetal lobe with a conical tip. 

 Branchiae 2, digitiform to ligulate, nonretractile; the upper one occurs 

 between the dorsal cirrus and notopodium, the lower one occurs 

 anterior to the ventral cirrus; they are thin walled and contractile, 

 with a thin layer of spiral muscle fibers. Proboscis with proboscideal 

 organs all similar, small, conical, flattened, with a central core and 

 surface marked with oblique furrows (fig. 55e). 



Biology. — Found at low water and dredged in deeper water on 

 bottoms of sand, mud, mud mixed with gravel, rocks, and particularly 

 in mud rich in detritus. Found in more exposed beaches than where 

 G. americana occurs, especially where the current flows swiftly. 

 Found in brackish waters and tidal estuaries. According to the 

 observations of Klawe and Dickie (1957), it is usually not found 

 deeper than 25 cm. and is more abundant in soft mud rich in organic 

 materials; relatively few were found in hard soils. It is a detritus 

 feeder, the food being retained and digested in the anterior portion of 



