10i COMMON SEAWEEDS. 



"beautiful, especially Porpliyra Laciniata. This is the 

 "best way of mounting it : Float the purple frond on 

 the paper, raise it gently, cover it with muslin in the 

 common way, but do not remove the muslin for two 

 or three days; meantime change the blotting paper 

 (which of course is laid over the muslin) very fre- 

 quently, and dry the paper at the fire, laying it on 

 quite warm; this so thoroughly dries the specimen 

 that it adheres perfectly to the paper. 



'Porpliyra varies in size and colour between the tide 

 marks — sometimes long and ribbon-like, violet or 

 purple; sometimes long, broad, and changes to reddish 

 purple and yellow. 



GIGAKTINA. 



(Name from the Greek word for a "grape stone," which the tubercles 

 resemble.) 



Generic character. — Frond cartilaginous, thread-like 

 or flat, irregularly divided ; purplish red. 



Fructification. — Of two kinds — external tubercles 

 containing spores, and tetraspores. 



Gigaktina Mamillosa. — This is the commonest 

 of four species found in our British tide-pools. It is 

 so like some varieties of Clwndrus Crispus that we 

 should fail to recognize it without close attention. 

 Observe the channelled frond, rough with papillcd, the 

 often broad forked tips. Cut a section of the frond, 

 and its periphery, or outside skin, is not simple cel- 

 lular membrane, but composed of delicate filaments, 



