TRANSACtrONS OP SECTION K. BSB 



close agreement with those of the few surviving genera of MarattiaceSe. The more 

 familiar type of sporangium met with in our existing fern-vegetation is also repre- 

 sented, and we have recently become familiar with several genera bearing spo- 

 rangia exhibiting a close resemblance to those of modern Gleicheniacese, Schizsea- 

 ceae, and Osmund acese. The sporangial characteristics of the different families of 

 living ferns are many of them to be found among PaljBOzoic 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 Palaeozoic forests must have been 

 the genus Cordaites : tall handsome trees, with long strap-shaped leaves, recalling 

 on a large scale those of the kauri pine of New Zealand. 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 genus Walchia, in habit almost identical with 

 Araucaria excelsa, the Norfolk Island pine, with Vlmannia and Voltzia, are 

 characteristic members of the vegetation belonging to the later phase of the Permo- 

 Carboniferous era. The Maidenhair-tree of the far East, one of the most vene- 

 rable survivors in our modern vegetation, is foreshadowed in certain features 

 exhibited by Cordaites and, as regards the form of its leaves, by Psyymophyllum, 

 Whittleseya, and other genera. Psyymophyllum is known to have existed in 

 Spitzbergen in the preceding Culm epoch, and Wittleseya occurs in Canadian 

 strata correlated with our Millstone Grit. Leaves have been found in Permian 

 rocks of Russia, Siberia, Western and Central Europe, referred to the genus 

 Baiera, a typical Mesozoic type closely allied to Ginkgo, In the upper Coal- 

 measures and lower Permian rocks a "few pinnate fronds have been discovered, 

 such as Sphenozamites, from the Permian of France, Pterophyllum from France 

 and Russia, and Plagiozamites from the Permian of Alsace, which bear a striking 

 likeness to modern Cycadean leaves. Throughout the Permo-Carboniferous era 

 the Cycadofilices formed a dominant group ; Lyginodendron, Medvllosa, Poroxylon, 

 and many other genera flourished in abundance as vigorous members of an 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 appear- 

 ance of Voltzia and other conifers with species of Equisetites, pioneer genera of 

 a succeeding era that constitute connecting links between the Palteozoic and 

 Mesozoic floras. 



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

 tinued, with comparatively minor changes, into the succeeding era, flourished over 

 a wide area in the northern hemisphere, suggesting, as White points out, an 

 almost incredible uniformity of climate. The same type of vegetation extended 

 as far south as the Zambesi in Africa, and to the vast coal-fields of China ; it 

 possibly existed also in high northern latitudes, but, since Heer's record of 

 Cordaites in Novaya Zemlya in 1878, no further traces of arctic Permo-Carbo- 

 niferous plants have been found. Calamites, Lepidodendron (with its near relative 

 SigiUaria), Ferus, Cycadofilices, Cordaites, and other Gymnosperms, constitute the 

 most familiar types. We have already noticed the existence in the southern 

 hemisphere of Lower Carboniferous and Devonian genera identical with plants 

 found in rocks of corresponding age within the Arctic circle. This agreement 

 between the northern and southern floras was, however, not maintained in the 

 later stages of the Palaeozoic epoch. Australian plant-bearing strata liomotaxial 

 with Permo-Carboniferous rocks of Europe, have so far aflbrded no examples of 

 SigiUaria, Lepidodetidron, or of several other characteristic northern forms; in 

 place of these genera we find an enormous abundance of a fern known as Glosso- 

 pteris, a type which must have monopolised wide areas, suggesting a comparison 

 ■with the green carpet of bracken that stretches as a continuous sheet over an 

 English moor. With Glossopteris was associated a fern bearing similar leaves. 



1903. 3h 



