22 
THE SEAWEEDS 
Our common plant is distromatic, and all its varieties may find a place 
among the eight named forms recorded by De Toni under TJlva lactuca of 
Linnaeus. The general description given by De Toni is: Frond 4in. to 
2ft. long, of variable outline, rounded, ovate, oblong, reniform, or lance- 
olate, undivided or irregularly laciniate, sometimes perforated, more or less 
waved or folded, shortly stipitate at the firmer cordate or cuneate base, or 
nearly sessile, with the margin usually quite entire. 
Another form met with not infrequently in Australia is Viva laetevirens 
of Areschong. The frond is divided nearly to the base into long twisted 
ribbons, the margins of which are abundantly and closely undulate. The 
membrane is very thin, pellucid, and the two layers of cells are easily 
separable in the upper parts, so that we have a transition to a well known 
form of Enteromorpha, E. linza. This form is of a deep green and grows 
in deeper water. 
LETTERSTEDTIA Areschoug. 
A genus allied to Viva , but differing in the possession of lateral 
quasi-foliar appendages, which subsequently fall off from the older parts 
of the main shoot, leaving it bare and irregularly toothed at the margin. 
The type species is from Natal, but J. Agardh described a species 
(L. petiolata) said to grow on some kind of sea-grass on the shores of New 
Holland. The locality is not indicated but it is an interesting form which 
should be looked for. 
Fig. 2 . — Letter stedtin insignis. (After G. Murray.) 
