120 HISTORY OF BRITISH ZOOPHYTES. 
Its head gracefully nodded (whence the appropriate specific 
appellation, xw¢ans, given to it by Sars), bending the upper 
part of its stem. It waved its long tentacula to and fro 
at pleasure, but seemed to have no power in contracting 
them. It could not by any means be regarded as an apa- 
thetic animal, and its beauty excited the admiration of all 
who saw it.’—#. Forbes and J. Goodsir. 
Tribe 2. SHRTULARINA. 
Famity SERTULARIAD A. 
Character. Polypidoms plant-like, horny, rooted, variously 
branched, tubular, filled with a semifluid organic pulp. Polypes 
contained within sessile cells, which are variously, but always de- 
terminately disposed along the sides of the main stalk or branch- 
lets, and are never terminal; ova contained in horny deciduous 
vesicles scattered over the polypidom ; embryos Planaria-like. 
Genus VIII. HALECIUM, Ofen. 
Gen. Char. Polypidom rooted, plant-like: the stem composed 
of aggregated subparallel capillary tubes; the branches alter- 
nate, spreading bifariously ; cells tubular, subsessile, jointed at 
the base, arising alternately from opposite sides, one under every 
joint of the branchlet: ovarian vesicles irregularly scattered. 
Polypes hydraform, scarcely retractile within their cells. 
