116 THE HISTORY OF CREATION, 
by the lower main-class, that of Gymnosperms. It was not 
until the secondary period that the higher main-class, that of 
Angiosperms, arose out of them. Of these also there existed 
at first only the lower groups without distinct corollas, the 
Monocotyledons and the Apetale. It was not until the 
chalk period that the higher Corollifloree developed out of 
the latter. But even this most highly developed group is 
represented, in the chalk period, only by the lower stage of 
Star-flowers, or Diapetale, and only at quite a late date, 
in the tertiary period, did the more highly developed Bell- _ 
blossoms, Gamopetalz, arise out of them, which at the same 
time are the most perfect of all flowering plants. Thus, in 
each succeeding later division of the organic history of the 
earth the vegetable kingdom gradually rose to a higher 
degree of perfection and variety. 
