NATURAL HISTORY OF CREATION. 69 



comparatively simple forms and structure. In the ranks 

 of the vegetable kingdom, the lowest place is taken by 

 plants of cellular tissue, and which have no flowers (cr?/;;- 

 togamia), as lichens, mosses, fungi, ferns, seaweeds. 

 Above these stand plants of vascvilar tissue, and bearing 

 flowers, in which again there are two great subdivisions ; 

 first, plants having one seed-lobe (^monocotyledons), and 

 in which the new matter is added within {endogenous), 

 of which the cane and palm are examples ; second, plants 

 having two seed-lobes [dicotyledons), and in which the 

 new matter is added on the outside under the bark 

 [exogenous), of which the pine, elm, oak, and most of the 

 British forest-trees are examples ; these subdivisions also 

 ranking in the order in which they are here stated. 

 Now it is clear that a predominance of these forms in 

 succession marked the successive ejjochs developed by 

 fossil geology ; the simple abounding first, and the com- 

 plex afterwards. 



Tvro-thirds of the plants of the carboniferous era ai-e 

 of the cellular or ciyptogamic kind, a proportion which 

 would probably be much increased if w^e knew the whole 

 Flora of that era. The ascertained dicotyledons, or higher- 

 class plants, are comparatively few in this formation; 

 but it will be found that they constantly increased as 

 the globe grew older. 



The master-form or type of the era was the fern, or 

 breckan, of wdiich about one hundred and thirty species 

 have already been ascertained as entering into the com- 

 position of coal.* The fern is a plant which thrives 

 best in warm, shaded, and moist situations. In tropical 

 countries, where these conditions abound, there are many 

 more species than in temperate climes, and some of these 



* The principal faiuilics arc named sphenoptcris, ncuropteris, and 

 pecoptei-is. 



