and browner. The substance is membranous and juicy, rather quickly de- 

 composing ; and in drying the plant adheres strongly to paper. 



At Plate XXXVII. of our first volume we have figured two 

 species of HalocUctyon ; one of them furnished with tetrasporic 

 fruit ; and we now present the third Austrahan species, furnished 

 with its cystocarpic fruit, clearly showing that the genus belongs 

 to the WiodomelacecB, and differs from Basya chiefly in the 

 structure of the frond. It is, so to say, as if the ramelli of a 

 Dasya, removed from the polysiphonous axis, were formed into 

 a tubular network, or we may compare it to Thuretia deprived 

 of the internal framework or skeleton. When this plant was 

 first observed, Sonder, by wdiom it was described, judging by 

 the Callithamnoid structure of its filaments, referred it to Cera- 

 itiiacecB, proposing for it the genus Hanowia. Agardh, while 

 adopting that supposed genus and retaining it among Cera- 

 miacecB, noticed its structural " analogy, if not affinity," with 

 Halodicfyon , a genus of Bhodomelacea, already founded on an 

 Adriatic Alga. Our knowledge of the fructification of the 

 Australian species is due to Mr. George Clifton, to whose many 

 discoveries among the Algae of Western Australia I have so 

 frequently to refer, and to whom I owe the only fruit-bearing 

 specimen of this curious Alga that I possess. 



Kg. 1. Halodictyon australe, — the natural size. 2. Portion of a branch of 

 the network. 3. A mesh, a ramulus, and a ceramidium. 4. Spores: — the 

 latter figures more or less magnified. 



