378 On the Genealogy of Plants, | [June, 
in the same formation, viz: the Chalk, and although their first 
actual appearance may date back into the Jura or Trias, it is 
probable that in point of time the two great classes of Angio- 
sperms had a nearly simultaneous origin. Whether either of 
these great vegetable types has reached its highest destiny on the 
earth it is impossible with certainty to affirm, but the indications 
are that, for the Dicotyle at least, progress in organization is still 
going on. 
In order to complete the systematic survey of the vegetable 
kingdom from the point of view of genealogical descent, the fol- 
lowing logical scheme of classification is appended for comparison 
with the genealogical scheme presented on a preceding page: 
$ 
Dicotylæ (exogenous) 
Angiosperms 
Monocotylæ (endogenous) 
Phænogams < 
Gnetaceæ 
Coniferæ 
Gymnosperms 
? (exogenous) 
f 
Cycadaceæ (endogenous) 
Ligulatæ 
Dichotomeæ 
Lycopodiaceæ 
Lepidophyta 
i Equisetaceæ (?) 
Cryptogams 
Rhizocarpeæ 
Filicineæ 
Filices 
{ 
ee a a S n a a 
. 
