eavities. Antheridia (in the males) on tufted, branching, parietal filaments, 
bright yellow, obovoid. Colour a dark olive, black when dry. Substance 
leathery and very tough, giving out much mucous matter in fresh water. 
The structure is very dense, of closely interwoven, branching and anastomo- 
sing filaments. 
It is impossible in a small plate to do justice to a plant which, 
when fully grown, is measured, not by zuches, but by fathoms, 
and which, to be seen in its true character, must be observed on 
the sea-shore. One of the full-grown fronds, such as are cast 
ashore at Port Fairy, is more than a sufficient load for a man. 
The ramification varies with age. Our Plate represents a very 
young frond; an older one may be split into many ribbons, each 
of them bordered with pinne; or it might be undivided, and 
bordered with many-times forked and attenuated segments. Kiit- 
zing’s genus Sarcophycus, founded on this species, is hardly worth 
retaining as distinct from D’ Urvil/ea, differing, as it does, merely 
on an inconstant character of ramification, and on a minor cha- 
racter in cellular structure. 
This Alga received the name pofatorum from Labillardiere, in 
consequence of his observing that the natives of Tasmania “ used 
portions of its great leaves, folded into the form of a pouch, for 
the purpose of keeping fresh water” (Zurn. /. c.) 
Fig. 1. D’URVILLHA POTATORUM, a very young plant, of the natural size. 2. 
Portion of the surface of a fertile frond,—slightly magnified. 3. Section 
through one of the male scaphidia, with tufts of antheridia,—more highly 
magnified. 
