V7 
Palaeophytelogy. : 429 
In the Cretaceous system appear the first dicotyle- 
donous trees. The lowest strata contain mostly marine 
plants, sea-weeds and sea-grasses, with a few trunks of a 
species of cypress which floated on the sea in the form of 
drift-wood. The fossil remains of the Middle Cretaceous are 
much richer. The Cycadez diminish in numbers ; but in 
their place appear the first exogenous trees, /wg/andites and 
Acerites, related to our walnuts and maples. Among the 
Ferns, which had hitherto formed almost the entire under- 
growth of the forests, rose shrubs allied to our willows ; 
alders and horn-beams, A/nzfes and Carfinites, attained the 
size of trees; and we find also allies of our J/yrica or 
sweet-gale. We have no certain knowledge of the existence of 
herbaceous Monocotyledons ; but certain impressions which 
bear a resemblance to lies or gingers make it probable. 
The marine and littoral plants of that system are similar in 
essential points to those of the Lower Cretaceous. ‘The 
Upper Cretaceous, including the Cyalk, affords only a very 
few vegetable remains, and those entirely of Algee. 
The lowest of the Zertiary or Cazinozoic rocks are the 
Hocene. (n this period dicotyledonous trees first begin to 
contest the supremacy with Cryptogams and Cycadez, and 
the entire outward form of the vegetation approaches that of 
ourtime. The lowest strata of this system furnish a marine 
flora consisting of sea-weeds. This is succeeded by a 
beautiful littoral flora, with Equisetaceze, Characee, and 
Naiadee. Land-plants finally appear ; and among these 
palms are especially conspicuous, and with them bananas, 
Myrtacee, Lauracee, and other exogenous and coniferous 
trees, which must, according to our present knowledge, have 
belonged to a tropical climate. Remains of the Ferns, 
Cupressineze, and Cycadez belonging to this system have 
been found in Greenland in 70° N. lat. We know of no 
country at the present time which affords a similar grouping 
of plants to the flora of the Eocene formation, taken as a 
whole. That of the basin of the Mississippi probably 
