GENERAL RELATIONS OF PLANTS TO TIME. 437 



of the Endogens, whilst the Angiosperraous Exogens are 

 doubtfully known by a single genus only, represented by 

 a single species. Upon the whole, therefore, the vegetation 

 of the Devonian period is characterised by the predominance 

 of Cryptogams and Gymnospermous Exogens. 



Passing on to the Carboniferous period, we have to con- 

 sider the largest and most varied of the Palaeozoic floras, but 

 one which is in most respects very similar to that of the 

 Devonian period. Some Devonian genera of plants do not 

 pass up into the over-lying formation, and some of the 

 Carboniferous genera have not been recognised in the 

 Devonian ; whilst hardly any species are common to the two 

 floras. Still, the general fades of the Carboniferous vegeta- 

 tion is much the same as that of the Devonian ; and the 

 same groups predominate in the former as in the latter. 

 The predominant groups of plants in the Carboniferous 

 rocks are the Ferns (Filiees), the Sigillarioids, the Lepido- 

 dendroids, and the Calamites, of which all except the Sigil- 

 larioids are certainly Cryptogams. Here, also, we have the 

 first instance of the occurrence of Fungi {Archagaricon, &c.) 

 The Coniferce are well represented by several genera (Arau- 

 carioxylon, Dadoxylon, &c.), but no remains of trees belong- 

 ing to the Angiospermous Exogens have been as yet detected. 

 There are, however, a few flowering plants (such as the 

 Monocotyledonous Fothocites of the Scotch Carboniferous). 

 Lastly, the Carboniferous rocks have yielded remains of the 

 genus Nmggerathia, referred by Brongniart to the peculiar 

 G-ymnospermous group of the Cycadacece, but regarded by 

 others as belonging to the Ferns. 



In the Permian period, the vegetation is nearly related to 

 that of the Coal-measures. We have still numerous Ferns 

 {Neuro'pteris, Pecopteris, Sphenojjteris), Tree-ferns (Fsaronms) , 

 the Lycopodiaceous Lepidodendron, and Calamites. The 

 Conifers, also, are abundant, and belong to several genera. 

 Some of the Conifers, however (as Ullmanici), bear genuine 

 cones, and the Sigillarioids, which are so characteristic of the 

 Carboniferous period, have apparently altogether disappeared 

 in the Permian. 



With the Trias we commence the sreat series of Mesozoic 



