CONFERVACE^. 281 



Rhizoclonium Casparyi. Dr. Caspary's Rhizo- 

 clonium. 



Threads extremely slender, very soft, long, curved, spurred 

 at distant intervals with short, root-like branches, woven into 

 a thin web of considerable extent ; cells varying in length, 

 in the same layer, and even in a single thread, from once to 

 six times the length of their diameter, filled with bright 

 green granular endochrome, the grains of which are of un- 

 equal size. 



This plant was first found by Dr. Caspary, at Falmouth 

 and Penzance. It is altogether more slender and deli- 

 cate than the normal state of R. riparium ; but it is 

 difficult to find definite characters whereon to base its 

 claim to be considered a distinct species. 



Rhizoclonium flaccum. The soft Rhizoclonium. 



Threads about an inch long, very slender, silky, straight 

 or slightly curved, simple or set with a few awl-shaped, root- 

 like branches, growing in patches on sea-weeds or floating 

 wood, attached at the base ; cells rather shorter than their 

 diameter, at first nearly filled with grass-green endochrome, 

 which is quickly condensed into a lens-shaped sporidium in 

 the middle of the cell, where it appears surrounded by a 

 broad transparent border. 



Kutzing has placed this species in the genus Hormo- 

 trichum, and Dr. Harvey in Lyngbya ; but the latter 

 author has at the same time expressed his approval of 

 the position assigned to it by the former. In these 

 circumstances I have hesitatated to deviate from the 

 course thus prescribed. But after careful consideration 

 I am of opinion that the root-like branches and the non- 



