176 
THE SEAWEEDS 
patent, broadly linear, flat, simple or pinnulate ; axils of pinnae rounded. 
Sori of tetrasporangia in the dilated apices of the ramuli. Height 30 cm. 
2 mm. to 6 mm. wide. Substance coriaceous, firm and tough. Colour a some- 
what livid-purple. 
Western Australia, South Australia (Encounter Bay, Eastern Bays) . 
Thysanocladia laxa Sonder. 
Greatly resembling the preceding, but with a conspicuous thin midrib in 
the pinnae. The laciniae often tricuspid. 
South Australia, Victoria, New South Wales. 
Thysanocladia oppositi folia (Ag.) J. Agardh. 
Holdfast a large disc nearly 2 cm. across. Stems usually dividing near 
the base into several long, simple, virgate secondary stems, each 10 cm. to 
40 cm. high, mostly denuded below, but for the greater part of their length 
closely feathered with opposite decompound pinnae. The segments narrow, 
subulate. The pinnae rigid and very closely opposed, often overlapping. 
Colour a very dark brownish-red, even blackening on drying. 
Western Australia and South Australia (Fowler’s Bay, Rivoli Bay, and 
Investigator Strait). - 
Fig. 46 . — Thysanocladia ovpositifolia: a, plant; b, a 
pinnated ramulus (plumule); c, cross- 
section cf the frond; d, cross-section of 
fertile ramulus and conceptacle; e, spore 
strings. (After Harvey.) 
