nearly terete; they vary much in form and comparative length and breadth ; 
the terminal one is almost always acute. The cystocarps are very rarely 
produced, and their structure not well ascertained; by Agardh the nucleus 
is described as consisting of obovate spores radiating from a centre and 
forming a globose mass, suspended among the central network of filaments 
in minute branchlets. e¢raspores are more frequent, but we have not found 
them in the Australian plant; they are oblong, zonate, and lodged in the 
periphery of the frond. The colowr is a very dark, dull purple, becoming 
almost black in drying. The suéstance is membranous and somewhat rigid, 
and the plant does not adhere to paper in drying. 
EEE 
The little Alga here figured is well known to European bota- 
nists, being common along the whole European seaboard, both 
Atlantic and Mediterranean; but in Australia, so far as we yet 
know, it is confined to Port Jackson harbour. ‘here, indeed, it 
is common enough in the two localities above given, and most 
probably exists in other parts of the harbour as yet unexplored. 
I find no appreciable difference between the Huropean and the 
Australian plant, and specimens collected by Dr. Hooker in New 
Zealand are very similar. 
Fig. 1. Carenetna Opuntia,—the natural size. 2. A frond from the tuft. 
3. Longitudinal section. 4. Transverse section :—magnified. 
