GROWTH METHODS. 



443 



TABLES OF GENERA. 

 The following tables of genera have been made possible by the courtesy of 

 Dr. F. H. Knowlton in furnishing data from his forthcoming catalogue of Mesozoic 

 and Cenozoic plants. The abbreviations indicate geological formations for the most 

 part, though States and regions are often designated as well by the usual abbre- 

 viations in so far as possible. The figures give the approximate number of species; 

 the absence of a figure indicates a single species. 



ABBREVIATIONS. 



'Revised by Dr. F. H. Enowlton. 



