144 
THE SEAWEEDS 
Gelidium rectangulare Lucas. 
Stem compressed, about 2 mm. wide, naked in lower third, above with long 
distichously-spreading branches. Height of plant to 30 cm. or more. Rami 
flat, distichously bipinnate. Ultimate pinnules numerous, opposite, 
pectinate, arising from the margins of the pinna at right angles, rigid, 
about 5 mm. long. Tetrasporangia as usual fringing the ultimate pinnules. 
Western Australia (Flinders Bay), South Australia (Point Le Hunte and 
Clare Bay at the head of the Great Australian Bight). 
PTEROCLADIA J. Agardh. 
Differs from Gelidium only in that the cystocarps are unilocular, and 
thus appear on the one face of the frond only. 
Pterocladia lucida (R. Brown) J. Agardh. 
Frond 15 cm. to 45 cm. high, plane compressed, thickened in the centre 
and sharply two-edged, pinnately decompound. Very variable in the amount 
Fig - . 19 . — Pterocladia lucida : a, plant; b, apex of a 
pinna, bearing conceptacles ; c, vertical 
section of a conceptacle and of the 
frond; d, apex of a pinna, bearing tetra- 
spores in dilated pinnulae; e, tetraspores. 
(After Harvey.) 
