510 Notices of Memoirs — 



succeeding era, flourislied 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 tlie northern and 

 southern floras was, however, not maintained in the later stages 

 of the PalfBOzoio epoch. Australian plant-bearing strata, homotaxial 

 with Permo-Carboniferous rocks of Europe, have so far afiforded. 

 no examples of SigiUaria, Zepidodendron, or of several other 

 characteristic northern forms; in place of these genera we find an 

 enormous abundance of a fern known as Glossopteris. With 

 Glossopteris was associated a fern bearing similar leaves, known as 

 Gangnmopteris, and with these grew Schizoneura and Phyllotheca, 

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

 others which bear a close resemblance to northern hemisphere types, 

 such as Noeggerathiopsis, a member of the Cordaitales, and several 

 species of Sphenopteris. Similarly, in many parts of India, 

 Glossopteris has been found in extraordinary abundance in the same 

 company with which it occurs in Australia. In South Africa an 

 identical flora is met with which extends to the Argentine and to 

 other regions of South America. It is clear that from South 

 America, through South Africa and India to Australia, there existed 

 a vegetation of uniform character which flourished over a vast 

 southern continent at approximately the same period as that which, 

 in the northern hemisphere and in China, witnessed the growth of 

 the forests whose trees formed the source of our coal-supply. 



Since attention was drawn by Dr. Blanford and other writers 

 to the facts of plant-distribution revealed by a study of the later 

 Palaeozoic floras, it has been generally admitted that during the Permo- 

 Carboniferous era there existed two fairly well-marked botanical 

 provinces. The more familiar and far richer flora occupied a province 

 stretching from the western states of North America across Europe 

 into China and reaching as far as the Zambesi ; the other province 

 was occupied by a less varied assemblage of plants, characterised by 

 the abundance of Glossopteris, Gangamopteris, Neuropteridium, 

 Noeggerathiopsis, Schizoneura, and other genera, stretching from 

 South America through India to Australia. 



In Brazil, Professor Zeiller has recorded the occurrence of a flora 

 including Zepidophloios, a well-known European member of the 

 Lycopods, associated with such characteristic southern types as 

 Gangamopteris and Noeggerathiopsis. Similarly, from the Transvaal 

 a European species of SigiUaria, with a Lepidodendroid plant, and 

 another northern genus, Psygmophyllum, have been found in beds con- 

 taining Glossopteris, Gangamopteris, Noeggerathiopsis, Neuropteridium, 

 and other members of the so-called Glossopteris flora. In India, 

 the Glossopteris flora exhibits an entire absence of Zepidodendron, 

 Calamites, SigiUaria, and other common northern genera, while 

 Sphenophyllum is represented by a single species. The Australian 

 Permo-Carboniferous flora is also characterised by the absence of 



