278 BRITISH SEA-WEEDS. {Rhochspermeo!.. 



1. Jania rubenSj Lavwvroux. 



Hab. Generally on the smaller Alcce. Dr. Johnston 

 says that it is not found on the coast of Berwickshire, and 

 that it is rare on the eastern shores of Scotland. It is 

 frequent on the English and L'ish shores. It is rare on 

 the coast of Ayrshire about Ardrossan and Saltcoats, but 

 not rare a little further north at Portincross, and very 

 abundant more to the south at Ballantrae, where I have 

 gathered a score of specimens in a quarter of an hour. It 

 is frequently found in the island of Arran. 



It grows in dense tufts from an inch to two inches 

 in height. Colour pale, but, when exposed to the sun, 

 it becomes whitish or at times greenish. Dr. Johnston 

 says that the structure of the axis is decidedly vegetable ; 

 and Dr. Harvey is of the same opinion. For an excellent 

 figure of it, natural size, and also for a magnified figure 

 after the crust has been removed by acid, see Johnston^s 

 ' History of British Sponges and Corallines^' and ' Phycologia 

 Britannica,' PL cclii. 



Genus LXXX. MELOBESIA, Lamouronx. 



Gen. Char. Frond attached or free, either flattened, orbicular, 

 sinuated, or irregularly lobed, or cyhndrical or branched (never 

 articulated), coated with a calcareous deposit. Fructification, 



