Samples of Dysidea herbacea collected at Pelorus Island,
Great Barrier Reef, Australia, afforded a new polybrominated diphenyl ether
(1). The structure was determined by n.m.r. two-dimensional methods and by an
X-ray diffraction study. N.m.r. spectral assignments for (1) and some
previously reported isomeric polybrominated diphenyl ethers are discussed.