TRANSACTIONS OF SECTION K. 881 



seeds constructed on tlie Gymnospermous plan, but characterised by an architec- 

 tural complexity far beyond that represented in the seeds of any modern Conifer 

 or Cycad. 



In such genera of Crymnospernis as Cordaites, Pifi/-^, and others, we have 

 examples of forest trees possessing wood almost identical with that of existing 

 species of Araucaria, but distini^uished by certain peculiarities whieh point to a 

 relationship with members of the Cycadoiilices, and suggest that Conifers as well 

 as Cycads may have sprung from a tilicinean stock. 



These waifs and strays from the vegetation of an era incredibly remote, when 

 strange amphibians were lords of the animal world, afford, as Newberry expresses 

 it, 'fascinating glimpses of the head of the column of terrestrial vegetation that 

 has marched across the earth's stage during the different geological ages.' 



Two facts stand out prominently as the result of a general survey of what are 

 practically the oldest records of plant-life. (_)ne is the abundance of types which 

 cannot be accommodated in our existing classification founded solely on living 

 plants. 



The Devonian and Lower Carboniferous plants lead us away from the 

 present along converging lines of evolution to a remote .stage in the history of 

 life ; they bring us face to fnce with proofs of common origins, which enable us to 

 recognise community of descent in existing gi'oups between which a direct alliance 

 is either dimly suggested or absolutely unsuspected if we confine our investigations 

 to modern forms. We recognise, moreover, in such a plant as Arcficeocalumites 

 an ancestor from which we may derive in a direct line the existing members of the 

 Equiaetales. In other types, by far the greater number, we see striking examples 

 of Nature's many failures, which, after reaching an extraordinary complexity of 

 organisation, gave place to other products of evolution and left no direct 

 descendants. 



Another fact that seems to stand out clearly is the almost worldwide distribu- 

 tion of several characteristic Lower Carboniferous plants. The accompanying table 

 (page 830), based on theartificial divisionsmarked outon the map, to which reference 

 has already been made, shows how widely some of the plants had migrated from 

 an unknown centre far back in a still more remote age. We are. as yet, nnable 

 to follow these Devonian plants to an earlier stage in their evolution. ^N'e are 

 left in amazement at their specialised structure and extended geographical distri- 

 bution, without the means of perusing the opening chapters of their history. 



Upper Carboniferous (Coal-AIeasures) and Permian Floras. 



From the Lower Carboniferous formation we pass on to the wealth of material 

 afforded by the Upper Carboniferous and Permian rocks. From the point of view 

 of both botanists and geologists, the fossil plants obtained from the beds associated 

 with the coal are of greater interest and importance than those of any other 

 geological period. By a fortunate accident our investigations are not restricted 

 to the examination of carbonaceous impressions and sandstone casts left by the 

 stems and leaves of the Coal-period plants. By means of thin sections cut from 

 the calcareous nodules of the coal-seams of Yorkshire and Lancashire, and from 

 the silicified pebbles of France and Saxony, it is possible to make anatomical 

 investigations of the coal-forest trees with as much accuracy as that with which 

 we can examine sections of recent plants. The differences betv/een the vegetation 

 that witnessed the close of the Carboniferous era and tliat which flourished during 

 the opening stages of the succeeding Permian epoch aie comparatively slight. It 

 has been demonstrated by Grand'Eury, Kidston, Zeiller, Potonie, and others, that 

 it is possible both to separate the floras of the Coal-measures from those of Lower 

 Permian age, and to use tlie plant species as trustworthy guides to the smaller 

 subdivisions of the Coal-measures ; liut apart from these minor dill'erences, the 

 general facies of the vegetation remained fairly constant during the Upper Carboni- 

 ferous and Lower Permian periods. 



The vast forests of the Coal age occupied an extensive area of land on the 

 site of the present United States of North America, stretching across Europe into 



