48 CAKBONIGENOUS ERA. 



five hundred species have been ascertained. The living plants 

 of our own era are at least 120,000, and it is difficult to sup- 

 pose the flora of that remote age to have been so much more 

 limited. It must, however, be observed, that there are many 

 conceivable circumstances to account for the non-preservation 

 or transmission of many of the plants of this era. The nume- 

 rous fungi, and other lowly forms, could scarcely have left clear 

 memorials of themselves in the rocks, or in the masses of coal ; 

 and it has even been ascertained by experiment, that some of 

 the highest forms of vegetation perish with surprising quick- 

 ness in water. If we might assume, nevertheless, that the 

 plants actually ascertained, form in any degree a representa- 

 tion of the flora of this period, they would imply that the 

 early terrestrial botany of our globe was greatly less varied 

 than the present, and composed chiefly of plants of compara- 

 tively simple form and structure. 



In the ranks of the vegetable kingdom, the lowest place is 

 taken by plants of cellular tissue, and which have no flowers, 

 (cryptogamiaj) as sea-weeds, lichens, mosses, fungi, ferns. 

 Above these, stand plants with vascular 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 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 the pine, elm, oak, and 

 all the British forest-trees are examples :) these subdivisions 

 also ranking in the order in which they are here stated. Now 

 it is found that the predominant plants of the coal era are of 

 the cellular and cryptogamic kind, while the dicotyledons are 

 comparatively rare. There is, indeed, one exogenous family, 

 which occurs in considerable numbers, and, perhaps, figured 

 more conspicuously in the living woods of that era than in the 

 dead coal beds namely, the conifers ; but this, again, is held 

 as the lowest family of its class, having an imperfection in its 

 flowering apparatus, which brings it into affinity with the 

 cryptogamic forms. That many trees of higher families now 

 existed, seems unlikely, when we learn that such trees occur 

 in considerable numbers in subsequent formations, showing 

 that there was nothing positively to forbid their being pre- 

 served in the coal measures, if they had then existed. 



A conspicuous form in this era was the fern or breckan, of 

 which about one hundred and thirty species have been ascer- 



