I02 THE HISTORY OF CREATION. 



In their organization Ferns rise considerably above Mosses, 

 and in their more highly developed forms even approach the 

 flowering plants. In Mosses, as in ThaUus plants, the entire 

 body is composed of almost equi-formal cells, little if at all 

 difierentiated ; but in the tissues of Ferns ^e find those 

 peculiarly difierentiated strings of ceUs which are called the 

 vessels of plants, and which are universally met with in 

 flowering plants. Hence Ferns are sometimes united as 

 " vascular Cryptogams " with Phanerogams, and the group 

 so formed is contrasted as that of the "vascular plants" 

 with "cellular plants," — that is, with " cellular cryptogams" 

 (Mosses and Thallus plants). This very important process 

 in the organization of plants — the formation of vessels 

 — first occurred, therefore, in the Devonian period, con- 

 sequently in the beginning of the second and smaller half 

 of the organic history of the earth. 



The branch of Ferns, or Filicinse, is divided into five 

 distinct classes : (1) Frondose Ferns, or Pteridse ; (2) Reed 

 Ferns, or Calamaria ; (3) Aquatic Ferns, or Rhizocarpese ; 

 (4) Snakes Tongues, or Ophioglossse ; and (5) Scale Ferns, 

 or Lepidophyta. By far the most important of these five 

 classes, and also the richest in forms, were first the Frondose 

 Ferns, and then the Scale-ferns, which formed the princi- 

 pal portion of the palaeolithic forests. The Reed Ferns, on 

 the other hand, had at that time already somewhat 

 diminished in number ; and of the Aquatic Ferns, we do not 

 even know with certainty whether they then existed. It is 

 difficult for us to form any idea of the very peculiar 

 character of those gloomy palaeolithic fern forests, in which 

 the whole of the gay abundance of fiowers of our present 

 flora was entirely wanting, and which were not enlivened 



