PART IV. 



CHAPTER LXIV. 



CLASSIFICATION AND GENERAL SUCCESSION 

 OF PLANTS IN TIME. 



The department of Palaeontology which deals with the relations of 

 Plants to time is usually spoken of under the name of Paleobotany 

 or Palaeophytology, and is one of wide extent and great complexity. 

 To render adequate justice to the vast body of knowledge which has 

 been accumulated as to the past history of plants, an amount of 

 space much exceeding that available in the present work would 

 be required. Moreover, the subject is one which cannot be 

 thoroughly dealt with except by a specialist, and which, in itself, is 

 of less importance to the general geological student than is Palaeo- 

 zoology. For these reasons, nothing more will be attempted here 

 than to give an extremely brief and entirely general sketch of the 

 past distribution and succession of the chief types of plant-life ; the 

 extinct groups being treated with somewhat greater detail than those 

 now in existence. In most cases, however, no description of the 

 characteristic structures of the different groups can be given ; nor 

 is it possible to introduce so much as a sketch of the general mor- 

 phology of plants. For such the student must be referred to works 

 devoted to structural Botany, to which he must also look for the 

 meaning of such technical terms as are here made use of. 



CLASSIFICATION. 



As regards the classification of Plants, the following table shows 

 the leading groups into which the existing members of the Vege- 

 table Kingdom are divided : — 



