stratum are pellucid, and consequently the articulated axial tube, which is 

 filled with strongly coloured endochrome, is distinctly visible ; and the 

 transverse ruguli or striae are also obvious, especially in dried specimens. 

 When barren the branches and ramuli are quite bare. When bearing 

 stichidia, these issue at short intervals throughout all the branches and 

 ramuli, and give the plant a racemose aspect. The stichidia are simple or 

 pinnate, opposite, and often in tufts, and are always involute at the tips ; 

 they contain a double row of tetraspores. Ceramidia unknown. Colour a 

 dark reddish-brown or brown-red, becoming much darker in drying. Sub- 

 stance membranaceous. The frond very imperfectly adheres to paper in 

 drying. 



A well-marked species of BytijjJdoea, and well named austral- 

 asica, being abundantly cast ashore on many parts of the south- 

 ern coast, and being the only Australian representative of the 

 genus commonly met with. One or two other species arc known 

 in Australia, but are among the rarer of the Algae. The genus 

 Bytiphloea has representatives in tropical seas, and in all the 

 warmer parts of the temperate zones ; and one or two outlying 

 species reach the coasts of Northern Europe. It differs from 

 Rhodomela by its more distinctly articulated axis and transversely 

 striate frond ; and from Polysiphonia, to which it is naturally 

 more nearly allied, by the total absence of articulated ramuli, 

 and by the tetraspores being (usually) confined to proper re- 

 ceptacles or stichidia. Prom Dictymenia it differs in wanting 

 a midrib, and in habit. 



Fig. 1. Eytiphlcea australasica, — the natural size. 2. Apex of a fertile 

 branch, with stichidia. 3. A stichidium. 4. A tetraspore. 5. Longitudinal 

 section of the frond. 6. Transverse section of the same: — the latter figures 

 magnified. 



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