100 On the Changes of the Vegetable Kingdom, S,'c. 



presented only species so far analogous in their most essen- 

 tial characters to those now existing, that they may be easily 

 classified in the natural families I have just named; the 

 other, more ancient, to which the vegetables belong whose 

 remains have produced great deposits of coal, and numerous 

 remains of which accompany beds of this combustible. The 

 latter recede much more widely from actually living forms, 

 enter with more difficulty into known families, evidently con- 

 stitute other families altogether distinct from those of our 

 actual creation, families whose existence has not been pro- 

 longed beyond this first geological period. 



The singular organisation and great dimensions of these 

 first inhabitants of our soil, have long thrown much obscurity 

 over the great classes of the existing vegetable kingdom. 

 Every day, however, the study of them is advancing, and 

 now we can no longer doubt that these gigantic vegetables, 

 so remarkable by their extraordinary forms and by their 

 structure, constitute special families, allied, however, to the 

 ferns and coniferse ; (that is to say, belonging to the great 

 divisions of vascular cryptogams, and gymnospermous pha- 

 nerogams.) 



In conjunction with many true ferns, often arborescent, 

 and with some coniferte, very different from those of our 

 climate, these vegetables must have formed vast forests gi'ow- 

 ing on a turfy soil, produced by their detritus, and to which 

 our coal owes its origin. 



Thus, briefly to recapitulate ; during the earliest periods of 

 the creation of living beings, the vegetable kingdom was 

 composed only of plants belonging to the two classes of that 

 kingdom distinguished by the simplest structure. These 

 plants had then special forms, were of considerable dimen- 

 sions, and the greater part constituted families now extinct. 



At a later period, chese two great classes still continued 

 to exist alone on the earth, but their forms approached more 

 to those which they pi'esent in the present vegetation ; the 

 families peculiar to the most ancient epochs were already 

 destroyed, and the numerous and varied families which wei'e 

 to appear in the tertiary epoch did not yet exist. 



Lastly, during this latter period, vegetation assumes cha- 



