OLIVE COLORED ALG^E. 107 



at the base. A quarter of the way up it is bare. From 

 that point it is thickly beset all around with short 

 branches, varying from half an inch to one and one- 

 half inches long, undivided, narrowly constricted at 

 the base, blunt at the apex, mostly curved, and stand 

 out perpendicularly from the main stem.. 



Q,Qv\\x%.— CASTAGNEA, Thuret, 



Castagnea Zosters, Thuret. 



This species is named from the "Eel grass" or 

 Zostera, on the fronds of which it commonly grows. 

 It is a very slender plant, not larger than a thread or 

 bristle, and some six or eight inches long, of a light 

 olive color, somewhat bent in a zigzag way, and but 

 sparingly branched. The branches are irregularly 

 placed, short (about one inch long), spreading horizon- 

 tally from the main stem, and either widely forking 

 or beset with twig-like branchlets, which are also fre- 

 quently forked or spiney. It adheres nicely to paper, 

 and is not an uninteresting though by no means a 

 handsome plant. I found it in August, in Marblehead 

 harbor. My correspondents do not report it else- 

 where, though Dr. Farlow records it in Wood's Holl, 



