284 Palaeontologie 



a special affinity with the Cycadales, and with the extinct 

 familv Cordalteae. 



Gymnospermous remains are common in the Palaeozoic 

 strata, but recent research has established the fact that the great 

 majority of their early representatives did not probably belong 

 to any existing families, but formed a distant group, the Cor- 

 dalteae, unrepresented at the present day. Cycadean remains 

 undoubtedly occur in the Palaeozoic rocks, though they are but 

 scanty, and far from numerous. On the other hand, there is 

 so far no proof of the existence of the Gnetaceae. 



The succession of Palseozoic floras, is briefly discussed. 

 No plant remains of Cambrian age are yet established, and 

 from Pre-Devonian rocks the evidence of plants other than 

 algae is still open to doubt. The high development of the 

 terrestial Devonian flora shows, however, that land plants must 

 have existed long before that period. Among these the presence 

 of Cordaitean leaves is remarkable, as indicating that Gym- 

 nosperms of high Organization already existed. A brief summary 

 of the Coal-Measure Floras of the Northern Hemisphere con- 

 cludes the Palaeozoic portion of the article. 



M e s o z o i c. 



The next section of this summary of our present knowledge 

 of plant remains, Starts with a consideration of the Permo- 

 Carboniferous (Glossopteris) flora of the Southern hemisphere. 

 A map is given showing its distribution. After noticing the 

 apparently world-wide, and uniform character of the flora of 

 the Lower Carboniferous, short descriptions are given of Glos- 

 sopteris, Phyllotheca and other prominent members of the 

 Glossopteris Flora. The remarkable and widely spread asso- 

 ciation of glacial deposits with Glossopteris bearing rocks is 

 also discussed. Certain groups such as the Lycopodlales, 

 Sphenophyllales, and possibly the Cordaltales, are noticed as 

 common to both the Northern and Southern Perrno-Carboni- 

 ferous floras, for it is now known that representatives of these 

 two floras co-existed in South America, South Africa, 

 and also, in the Northern hemisphere in Russia. In the latter 

 case, this association of types clearly points to a penetration 

 of representatives of the Glossopteris Flora to the North of 

 Europe towards the close of the Permian period. 



The Rhaetic and jurassic Floras, which succeed the Glos- 

 sopteris flora in the Southern hemisphere, differ but slightly 

 from the contemporanous Northern Floras, and this points to 

 a uniformity in the Vegetation of these periods, which is in 

 contrast to the existence of two botanical provinces in the latter 

 part of the Palaeozoic period. 



Our knowledge of Triassic Vegetation is far from extensive, 

 but among the plants from the Lower Triassic strata there are 

 a few which form connectinsr links with the older Permo- 

 Carboniferous flora, although there is a marked difference as a 

 whole between these two floras. There is evidence of a distinct 



