241 



GRASS-GREEN SEA OR FRESHWATER WEEDS- 

 CHLOROSPERME.E. 



Fronds Grass-green, or in a few instances Purple or Olive, or 

 very rarely Red. Propagation by simple cell division ; by 

 the transformation of the colouring-matter of the cells into 

 zoospores ; or, occasionally, by ordinary spores developed 

 in proper spore-cases. 



Comparatively few of the plants belonging to this 

 division are marine. The remainder grow in fresh- 

 water streams, ponds and ditches, or even in damp 

 places where there is no water. Their characters are 

 not yet well understood, and in consequence many of 

 the genera and species are but imperfectly determined. 

 That portion only of the division which is marine will 

 be described in this work. 



Order XXI. SIPHONACE^]. 



Frond consisting of a single, filiform, branching cell, or of a 

 sponge-like mass of many such cells interwoven; either 

 naked or coated with carbonate of lime. 



All the genera of this Order which are represented 

 on our coasts belong to the section which is destitute 

 of calcareous coating. They are very different from 

 each other in external appearance, but their structure, 



R 



