POLYCHAETE WORMS, PART 1 105 



prostomiiim, next 2 tentacular segments distinct, each with 2 pairs of 

 tentacular cirri. Tentacular cirri slender, without articulations, sim- 

 ilar in shape and length to doreal cirri. Dorsal cirri long, slender, 

 articulated, alternately longer and shorter, about equal in length to 

 body width. Neuropodia cylindrical, tapering to bluntly conical 

 processes. Neurosetae compound, with blades long to short. 



Proboscis eversible, with large inflated basal portion and smaller 

 cjdindrical terminal portion, without jaws or papillae. Color, in 

 life: dark rusty brown or blackish dorsally and ventrally including 

 prostomium, usually with lighter transverse bands — may be 3 per 

 segment; eyes reddish; in alcohol: colorless. 



Biology. — A small but active worm found at low water on muddy 

 sand flats, under stones, among eelgrass, on shells, on pilings among 

 hydroids, ascidians, etc. Dredged among shells, sponge masses, 

 clumps of algae, especially common in "weed" in Vineyard Sound, 

 among ascidians (as sandy Arnaroecium) . Found in salt ponds 

 (Charlestown Pond, Rhode Island, H. P. Jefferies). 



It shows commensalistic tendencies, having been found among the 

 spines of the sea urchin Lytcchinus and on the oral surface of echino- 

 derms (Florida, Hartman, 1951), and with the terebellid Lysilla alba 

 (West Falmouth Harbor, Massachusetts, 1954); it was also found 

 inside the sea cucumber Thyone (Woods Hole; it came out when the 

 cucumber was being injected with magnesium chloride solution, J. F. 

 Hickok, August 1953). 



It becomes sexually mature during July and August, the females 

 appearing brown, with brownish eggs, the males cream colored. They 

 may come out at night in vast numbers, swimming at the surface; they 

 are attracted to light. The eggs are laid in the evening between 7 and 

 10 o'clock; artificial fertilization is possible if the eggs have been ex- 

 truded, not otherwise (Treadwell, 1901). According to Moore (MS.), 

 the species lends itself admirably for regeneration and grafting experi- 

 ments. Bifid monsters and abnormalities of segmentation are 

 common. 



Material examined. — Type specimen from Vineyard Sound. 

 Also numerous specimens from Massachusetts (Cape Cod, Vineyard 

 Sound, Buzzards Bay), Rhode Island, Connecticut, North Carolina, 

 Georgia, Florida (Cedar Keys, E. L. Pierce, March 9, 1955; Seahorse 

 Key, J. Taylor, 1960), in low water to 458 fathoms. 



Distribution. — Massachusetts (Cape Cod) to Florida, Gulf of 

 Mexico (Florida, Mexico), Bermuda, West Indian region and Carib- 

 bean Sea. Low water to 458 fathoms; surface. 



