2 



DESCRIPTION OF THE THREE SERIES. 



Several of the most perfect Confervae and Siphonise 

 grow beyond the reach of ordinary tides ; and others are 

 sometimes dredged from very considerable depths. The 

 greater mass, however, of the green-coloured series are 

 considerably submerged. 



The olivaceous brown, or olive-green series, is almost 

 entirely confined to marine species, and is, in the main, 

 characteristic of those that grow at half-tide level, be- 

 coming less frequent towards low-water mark ; but it 

 frequently occurs also at greater depths, in which case 

 it is very dark, and passes into brown, or almost black. 



The red series, also, is almost exclusively marine, 

 and reaches its maximum in deep water, though some 

 varieties occur at half-tide level. When above this, 

 they assume either purple, orange, or yellow tints, 

 and sometimes even a cast of green. They are, how- 

 ever, very rarely pure red much within the range of 

 extreme low-water mark, higher than which many of 

 the more delicate species will not vegetate : and those 

 that do exist, degenerate in form, as well as in colour, 

 as they recede from it. How far below low-water mark 

 the red species extend, has not been ascertained ; but 

 those from the extremest depths of the sea that we are 

 acquainted with, are of the olive series in its darkest 

 form. 



In the ' Manual of British Algse,' published by Dr. 

 Harvey, he says : — " Among plants in general nothing 



OS! 



