1 64 HISTORICAL PALEONTOLOGY. 



the Carboniferous period is so great, that nothing more can be 

 done here than to notice briefly the typical and characteristic 

 groups of these such as the Ferns, the Calamites, the Lepido- 

 dendroids, the Sigillarioids, and the Conifers. 



In accordance with M. Brongniart's generalisation, that 

 the Palaeozoic period is, botanically speaking, the "Age of 

 Acrogens," we find the Carboniferous plants to be still mainly 

 referable to the Flowerless or " Cryptogamous" division of the 

 vegetable kingdom. The flowering or "Phanerogamous" 

 plants, which form the bulk of our existing vegetation, are hardly 

 known, with certainty, to have existed at all in the Carbon- 

 iferous era, except as represented by trees related to the existing 



Fig. 108. Odontopteris Schlotheimii. Carboniferous, Europe and North America. 



Pines and Firs, and possibly by the Cycads or "false palms."* 

 Amongst the " Cryptogams," there is no more striking or 

 beautiful group of Carboniferous plants than the Ferns. .Re- 

 mains of these are found all through the Carboniferous, but in 

 exceptional numbers in the Coal-measures, and include botli 

 herbaceous forms like the majority of existing species, and 

 arborescent forms resembling the living Tree-ferns of New 

 Zealand. Amongst the latter, together with some new types, 

 are examples of the genera Psaronius and Caulopteris, both of 



* Whilst the vegetation of the Coal-period was mainly a terrestrial one, 

 aquatic plants are not unknown. Sea-weeds (such as the Spirophyton 

 cauda-Galli) are common in some of the marine strata ; whilst coal, 

 according to the researches of the Abbe Castracane, is asserted commonly 

 to contain the siliceous envelopes of Diatoms. 



