1604 HISTORICAL PAILAZONTOLOGY. 
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 Paleozoic 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 
x“ 
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 both 
herbaceous forms like the majority of existing species, and 
arborescent forms resembling the living Tree-ferns of New 
Zealand. Amongst the latter, together Sh 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 S#rxophyton 
cauda-Galli) are common in some of the marine strata; whilst coal, 
according to the researches of the Abbé Castracane, is asserted commonly 
to contain the siliceous envelopes of Diatoms. 
