ISO BRITISH SEA- WEEDS. {JRIioclospermece. 



12. CaLLITH AMNION TETRAGONUM, Agctrdk. 



Hab. On the larger Algse. Annual. Summer. On the 

 shores of England, Ireland, and also Scotland. It is occa- 

 sionally found on the Ayrshire coast, and in the island of 

 Arran. 



Professor Harvey says, in his Phyc. Brit., PI. cxxxvi., 

 " When fully grown (four or five inches in height), this is 

 one of the largest and most robust and shrubby British 

 species of this charming genus, and seen under the water 

 is an object of much beauty. In drying, though it suffi- 

 ciently retains its form, it loses considerably in elegance, 

 from the pressing together of the delicate quadrifarious 

 ramuli, which become confounded with each other.'^ It 

 rapidly changes colour in fresh water, assuming a brilliant 

 orange tint, and giving out a rose-coloured powder. 



13. Callithamnion brachiatum, Bonnem. 



I have been favoured with fine specimens of this by Miss 

 A. Griffiths. It is very like C, tetragonwn. 



14. Callithamnion byssoideum, Arnott, 



Hab. On other Alga^. Whitsand Bay, Dr. Walker Arnott; 

 Devonshire, Mrs. Griffiths; Salcombe, Mrs. Wyatt; Strang- 

 ford Lough, Mr. W. Thompson. We do not know that it has 

 been found in Scotland. We have fine specimens of it from 

 Mrs. Owens and l\Iajor ^lartin, got by them in Lough Swilly. 



