474 Palaeontologie. 



Prominent among the Gymnospenns of the Palaeozoic fo- 

 rests must have been the genus Cordaites: tall handsome trees, 

 with long strap-shaped leaves. This genus, vvhich has been 

 made the type of a distinct group of Gymnospenns, 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 mcre 

 definite coniferous types made their appearance. The Maiden- 

 hair-tree of the far East, one of the most venerable survivors 

 in oiir modern Vegetation, is foreshadowed in certain features 

 exhibited by Cordaltes and, as regards the form of its leaves, 

 by Psygmophyllum, Whittleseya, and other genera. Leaves have 

 been found in Permian rocks ofRussia, Siberia, Western 

 and Central Europe, referred to the genus ßaiera, a typi- 

 cal Mesozoic type closely allied to Ginkgo. In the upper Coal- 

 measures and lower Permian rocks a few pinnate fronds have 

 been discovered, vvhich bear a striking likeness to modern 

 Cycadean leaves. Throughout the Permo-Carboniferous era 

 the Cycadofilices formed a dominant group ; Lyglnodendron, 

 Mediillosa, 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-Iike 

 fronds already referred to ; also the appearance of Voltzia and 

 other conifers with species of Equisetites, pioneer genera of a 

 succeeding era that constitute connecting links between the 

 Palaeozoic and Mesozoic floras. 



What we may call the typical Vegetation of the Coal- 

 measures, which continued. with comparatively minoi 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. 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. Austra- 

 lian plant bearing strata homotaxial with Permo-Carboniferous 

 rocks of Europe^ have so far afforded no examples of Sigil- 

 laria, Lepidodendron, or of several other characteristic northern 

 forms; in place of these genera we find an enormous abun- 

 dance of a fern known as Glossopterls. With Glossopterls was 

 associated a fern bearing similar leaves, known as Gangamop- 

 tei'is, and with these grew Schlzoneiira and Phyllotheca. mem- 

 bers of the Equisetales. In addition to these genera there are 

 others which bear a close resemblance to northern hemisphere 

 types, such as Noeggerathiopsls, a member of the Cordaitales, 

 and several species of Sphenopteris. Similarly, in many parts 



