162 PAST AND PRESENT 
or Mesozoic epoch the group of the Cycads, to which 
our modern Screw-pines belong, rose to great impor- 
tance, descended probably from the Pteridosperms, 
and long continued to be a dominant feature of 
terrestrial vegetation. And then at last in the Lower 
Cretaceous rocks the Angiosperms, or “Flowering 
Plants” par excellence, both Dicotyledons and Mono- 
cotyledons, put in an appearance. It seems probable 
that they were evolved from Cycads, such as the 
Bennettiteg@, recent researches on magnificent fossil 
material discovered in America showing striking 
analogies between certain Cycadaceous flowers and 
those of such plants as Magnolias, Water Lilies, and 
Buttercups. Once established, the Angiosperms rose 
to primary importance in an extraordinarily short 
time—very possibly owing to the “invention” of 
insect pollination, which may have arisen at that 
period. In Upper Cretaceous times the two great 
groups into which the Angiosperms still fall, the 
Dicotyledons and Monocotyledons, fairly dominated 
the flora of the world, as they do at present. Already 
many types familiar at the present day had appeared, 
and the woods were filled with Birches, Beeches, 
Oaks, Planes, Maples, Hollies, Ivies, as they are 
nowadays. 
The record of the rocks during these long periods 
of time contains not only the story of the rise of the 
great divisions of the vegetable world, but also of 
the decline of most of them. A few, like the Pteri- 
dosperms and the Sphenophylls, died out completely 
long ago; but most of the great groups of early days, 
such as Cycads, Ferns, Horsetails, and Club-mosses, 
still survive, though shorn of much of their glory. 
