io STUDIES IN FOSSIL BOTANY 



showing structure belong to these two classes. So far 

 as the Carboniferous formation is concerned, silicified 

 specimens are -characteristic of the French fossil flora, 

 while calcified remains prevail in the English coal-fields. 

 The former have become classic through the investiga- 

 tions of Brongniart and Renault, the latter through 

 those of Witham, Binney, Williamson, and others. In 

 good specimens of both kinds, the whole microscopic 

 structure is often preserved with marvellous perfection. 

 It has been alleged that the French silicified specimens 

 are the more perfect of the two, but, beautiful as they 

 are in many cases, the calcareous petrifactions are on 

 the whole superior to them in the preservation of 

 structure. In the calcified specimens the actual organic 

 substance remains, though chemically altered. The 

 entire network of cell-walls, sometimes showing even 

 their most delicate markings, traverses the matrix ; in 

 the cavities some remains of the cell-contents are often 

 preserved. 



The following analyses, which the authors have 

 kindly permitted me to reproduce, are from a forth- 

 coming paper by Miss M. C. Stopes, D.Sc, and Mr. 

 D. M. S. Watson.: — 



