134 Dr. F. 0. Bower [April 30, 



found in Sweden and in Scotland in greater profusion than ever 

 before, while the Scottish specimens are so well preserved that they 

 are now almost as well known in structural detail as plants of the 

 present day. Already in this room repeated lectures have been given 

 on the Palaeozoic Flora. Many plants of the Carboniferous Period 

 have been described here in microscopic detail, and they are mostly 

 referable to affinity with such living types as Ferns, Club-Mosses and 

 Horsetails. Some, such as the Sphenophylls and Pteridosperms, 

 represent classes which have since died out. But, speaking generally, 

 the flora of the coal is composed of plants comparable with the 

 lower vascular plants now living. They possessed stems, leaves, 

 roots and sporangia. Some even produced seeds like modern 

 (Jymnosperms. 



Passing back from the Carboniferous Period to the Upper 

 Devonian, the flora, though more restricted, may still be described 

 in terms applicable to the living vegetation. They include among v 

 others the gigantic fern-like plant, Archseopteris Mbernica, from 

 Kiltorkan, Co. Kilkenny ; the large Lycopod Bothrodendron, from 

 the same source : and the large-leaved Psevdobornia, from Bear 

 Island. Flat leaf-expansions are here seen, and the plants named 

 have been referred in their general characters respectively to affinity 

 with the Ferns, Club-Mosses and Horsetails. But between the 

 Upper Devonian and the Lower, geologists tell us that a vast period 

 of time intervened. The evidence of the plant-remains supports 

 this. The Lower Devonian fossils so far known are meagre in 

 number of forms. In their characters they differ more markedly 

 from the plants of the present day than any of their successors. 

 They were rootless, and there appears to be a complete absence of 

 large flattened leaf-expansions. It is upon them that the new dis- 

 coveries have shed so interesting a light. Conversely, that light is 

 reflected back by comparison upon the more recent forms. In fact,. 

 a new chapter has been opened in plant-morphology, and a new class 

 of vascular plants, the Psilophytales, has been established to receive 

 these representatives of the oldest known land flora. The study of 

 them is leading to new interpretations of the form shown by plants 

 of later periods, and ultimately of the present day. 



Until 1913 the plants of the Lower Devonian Rocks were 

 very imperfectly known. Their recognised characters were chiefly 

 negative. There was no evidence of broad leaf -surfaces, nor was it 

 clear whether or not they bore leaves as distinct from stems. The 

 existence of true roots was also doubtful. The best known plants 

 were constructed of approximately cylindrical stalks bearing lateral 

 spines. These stalks arose from a branched and creeping base. 

 Some of them showed crozier-like curves when young, and 

 sporangium-like bodies were sometimes found upon them. The 

 most distinctive of these plants were grouped by Dawson in his 

 genus Psilophyton, and he published a drawing of his reconstruction 



