168 U.S. NATIONAL MUSEUM BULLETIN 2 27 



Biology. — The species is notably euryhaline. It is found from 

 moderately high tide line to subintertidal levels, under strictly 

 marine conditions and ascending tidal streams to brackish water where 

 it may be able to Avithstand considerable flooding of fresh water. 

 Thus it is found in bays, estuaries, marsh ditches, and mangroves. 

 It is found in a great variety of niches in the intertidal area, in 05^ster 

 beds where it may form burrows in the crevices of the oyster shells 

 (along with Polydora and Hydroides), among barnacles, mussels, 

 and sponge masses. It is found on the under sides of rocks and 

 stones or boards, on pilings of wharfs among barnacles and ascidians. 

 It may occur in old tubes of Diopatra, Maldanopsis, Hydroides, 

 and Polydora. It is found on sandy shores, especially where there is a 

 mixture of mud with the sand, in coarse sand, in stiff muddy sand, in 

 gravelly and shelly mud, in peat, in soft mud of brackish water 

 regions; it may occur in very foul soft mud. It has also been dredged 

 in mud. 



It forms typically a broad U-shaped burrow, open to the surface at 

 both ends. It can burrow rapidly. It prefers coves and harbors, 

 bays and sounds, not exposed beaches of moving sand; the burrows 

 may be semipermanent or more or less temporary, the worms crawling 

 within the burrows, the anterior end extending out some distance 

 from the burrow and withdrawing back rapidly. It may also live 

 with the head end downward with the posterior end close to the 

 surface or protruding. New burrows are constructed frequently. 



It is extremely abundant in Great Bay, New Hampshire and the 

 rivers leading into it. In New Jersey, it is common everywhere in the 

 harbor except in pure sand. It is common in Delaware Bay, the most 

 flourishing community being in the midbay region where the salinity 

 averages between 20 to 21 parts per thousand (Amos, 1957). It is the 

 most common annelid in Chesapeake Bay. It is the commonest 

 and most widely distributed nereid in the vicinity of Beaufort, North 

 Carolina. It is very abundant in many intertidal areas in the Gulf of 

 Mexico. It no doubt serves as an important food item to bottom- 

 feeding animals such as crabs and skates. 



The swarming sexually mature adults may be found in immense 

 numbers, in the daytime and evening, when they are attracted to the 

 light. They have been reported swarming in Miramichi Bay, New 

 Brunswick, in June (Berkeley and Berkeley, 1953) ; they were swarming 

 in such large numbers that a fisheries patrol boat at first mistook the 

 swarm for a sand bar; the surface of the sea over a wide area was in a 

 state of violent turmoil. In the Woods Hole region and Vineyard 

 Sound, they have been observed swarming in March, May, June, July, 

 August, September, first of October (Bumpus, 1898a-c; Wilson, 1892). 

 They were seen in large numbers in Rhode Island in May (Mead, 



