ALG.E. 
171 
Professor Lindley remarks concerning 
the tribe most frequently found fossil in the 
transition rocks, Algae are most important 
in the economy of nature for forming the 
commencement of soil by their deposits and 
decomposition. The basin of the ocean is 
said to be continually rising by the deposit 
of such plants, particularly of conferva 
chthonoplastes, the closely aggregated fibres 
of which form dense beds. We find latitude, 
depths, currents, influencing the forms of 
algae in nearly the same way as latitude, 
elevation, and station, affect those plants 
which are more perfect. The number of 
species is scarcely capable of being esti¬ 
mated.”^ 
Although the oceans occupied so much of 
the ancient earth at various periods of its 
history, yet the modern developement of 
marine vegetation is larger than we have any 
example ot in former time. 
Algae and their traces are sometimes 
found in isolated fragments in the older 
rocks; probably many of the carbon- 
* Lindley’s Introduction to Botany, 341 . 
