RED ALG^^. 189 



direction, the longest near the bottom. These 

 branches are often branched in the same manner, 

 and sometimes the branchlets also. All the parts are 

 beset, sometimes thickly, sometimes sparingly, with 

 short, horizontal spines one-tenth to one-third of an 

 inch long. 



The distinguishing mark of the plant is this : The 

 almost or quite naked extremity of the principal 

 branches is turned back at the ends so as to form 

 a hook, often not unlike a fish-hook in appearance. 

 This must not be mistaken for the twining tendrils 

 borne on the end branches of one variety of Cysto- 

 c Ionium purpurascens. The color is a dark, dull 

 red, with a purplish tinge, which rapidly fades to 

 dirty green and white, when exposed to sunshine or 

 the action of fresh water. It adheres to paper, but 

 not very strongly. 



Order.— RHODYMENIE^. 

 Ger\us.— RBODYMENIA* Grev. 



Rhodymenia palmata, Grev. 



The palmate or hand-shaped Rhodymenia is so 

 common and so universally known under the common 



* Rhodymenia = A red membrane. 



