Life Progressive. 415 
wonderful dicotyledonous flora of the Upper Cretaceous 
similarly surprise us without any prophetic annunciation 
from the older Jurassic. Many other instances might be 
cited, but enough has been said to show that the problem 
is one envirored with profound difficulties. 
As we pass from the older rocks into the newer, we not 
only find that the animals of each successive formation 
become gradually more and more like existing species upon 
the globe, but we also find that there has been a gradual 
MESOZOIC FLORA AND FAUNA. 
Cycads, Pandanus, Deinosaurs, Birds and Pterodactyl. 
progression and development in the types of animal life 
which characterize the geological ages. Taking the earliest- 
known and oldest examples of any given group, it can some- 
times be shown that these primitive forms, even though they 
are highly organized themselves, possessed certain charac- 
ters such as are now only to be met with in the young of 
their existing representatives. Such characters, which are 
technically called embryonic characters, do not prevent the 
frequent attainment by their possessors of sizes much more 
