Professor A. C. Seward — Floras of the Past. 509 



against tlie stems of stronger plants. Lycopods, with trunks as 

 thick and tall as forest trees, were among the most vigorous members 

 of the later Palgeozoic forests. Although recent research has shown 

 that several of the supposed ferns must be assigned to the Cycad-fern 

 alliance, there can be no doubt that true ferns had reached an 

 advanced state of evolution during the Permo-Carboniferous_ epoch. 

 The abundance of petrified stems of the genus Psaronius, of which 

 the nearest living representatives are probably to be found among the 

 tropical Marattiaceae, demonstrates the existence of true ferns. The 

 most striking fact as regards the Permo-Carboniferous ferns is 

 the abundance of fertile fronds bearing sporangia which exhibit 

 a more or less close agreement with those of the few surviving 

 genera of Marattiacege. The more familiar type of sporangium met 

 with in our existing fern-vegetation is also represented, and we have 

 recently become familiar with several genera bearing sporangia 

 exhibiting a close resemblance to those of modern Gleicheniacese, 

 Schiza^aceEe, and Osmundaceee. The sporangial characteristics of the 

 different families of living ferns are many of them to be found 

 among Palasozoic types, but there is a frequent commingling of 

 structural features showing that the ferns had not as yet become 

 differentiated into so many or such distinct families as have since 

 been evolved. 



Prominent among the Gymnosperms of the Paleeozoic forests must 

 have been the genus Cordaites : tall handsome trees, with long 

 strap-shaped leaves. This genus, which has been made the type of 

 a distinct group of Gymnosperms, combined the anatomy of an 

 Araucaria with reproductive organs more nearly allied to the flowers 

 of Cycads, and exhibiting points of resemblance with those of the 

 Maidenhair- tree. It is not until the later stages of the Permo- 

 Carboniferous epoch that more definite coniferous types made their 

 appearance. The Maidenhair-tree of the Far East, one of the most 

 venerable survivors in our modern vegetation, is foreshadowed in 

 certain features exhibited by Cordaites and, as regards the form of its 

 leaves, by Fsyginophyllum, Whittleseya, and other genera. Leaves 

 have been found in Permian rocks of Eussia, Siberia, Western and 

 Central Europe, referred to the genus Baiera, a typical Mesozoic 

 type closely allied to GinTcgo. In the Upper Coal-measures and 

 Lower Permian rocks a few pinnate fronds have been discovei'ed, 

 which bear a striking likeness to modern Cycadean leaves. 

 Throughout the Permo-Carboniferous era the Cycadofilices formed 

 a dominant group ; Lyginodendron, Medullosa, Poroxylon, and many 

 other genera flourished in abundance as vigorous members of aa 

 ancient class which belongs exclusively to the past. 



One distinctive characteristic of the vegetation of later Permo- 

 Carboniferous days is the occurrence of the Cycad-like fronds already- 

 referred to ; also the appearance of Voltzia and other conifers with 

 species of Eqiiisetites, pioneer genera of a succeeding era that con- 

 stitute connecting links between the PalEeozoic and Mesozoic floras. 



What we may call the typical vegetation of the Coal-measures, 

 which continued, with comparatively minor changes, into the 



