On the Plants of the World before Man. 271 
displacement of the axis of the planet; the internal heat of 
of the primitive and secondary epochs. 
In treating the subject, Saporta adopts the natural plan of 
considering the plants, so far as they are known by their re- 
. Yor Primordial, Paleozoic and Mesozoic times, the examina- 
ton is limited to what is generally known.t The Primordial 
* See on this subject an article of J. S. Gardner, in Nature, Dec. 12, 1878. h 
tSaporta divides the whole fossil vegetable world in four great epochs, the 
fame as those recognized by Geolo i : . 6 
ambrian, Silurian); 2. Paleozoic (Devonian, Carboniferous, Permian); 3. Meso- 
Zoic (Triassic, Jurassic, Cretaceous), and 4. Neozoic for the Tertiary. 
