That this plant belongs to Agardh’s genus Helminthocladia, 
founded on the H. purpurea of the coasts of Europe, there can 
be little doubt. My only doubt respecting it is, lest it should 
not be sufficiently distinct specifically from /7. purpurea itself, 
which is a very variable plant, and to some of whose varieties 
our plant bears considerable resemblance. In general, there is 
more difference in diameter between the main stem and its 
branches in the European than in the Australian plant; the 
Australian is also more densely branched, grows in more crowded 
tufts, and is of a paler and duller colour. Still, I cannot point 
to any very definite characters by which it may be distinguished. 
Fig. 1. HeLMINTHOCLADIA AUSTRALIS,—the natural size. 2. Cross section of 
a branch. 8. Partial longitudinal section, showing the arrangement of the 
axile threads, and those of the periphery :—the latter figures magnified. 
