Notices of Memoirs — Vegetation of tJie Coal Period. 20' 



II. — British Association for the Advancement of Science. 

 Bradford, 1900. Joint Discussion, Sections C and K. On 

 THE Conditions under which the Plants of the Coal 

 Period grew. 



1. Flora of the Coal-bieasures. By K. Kidston, F.R.S.E., F.G.S. 



LEAVING out of consideration a few genera of which we possess 

 little or no definite knowledge, the flora of the Coal-measures 

 consists of Ferns, Calaraites, Lycopods, Sphenophylleai, Cordaites, 

 and Conifera^. 



In genera and species the Ferns are probably more numerous than 

 the whole of the other groups, and contain representatives of the 

 Eusporangiate and Leptosporangiate members of the class. The 

 Eusporangiate, or those ferns whose sporangia are unprovided with 

 an annulus, were more numerous in the Carboniferous period than 

 at present, though in the Coal-measures they do not appear to have 

 been more numerous than the genera with annulate sporangia. Tree 

 ferns, though not very common, are more frequent in the Upper 

 than in the Lower Coal-measures, in the lowest beds of which they 

 seem to be very rare. 



The Calamites are largely represented throughout the whole of 

 the Coal-measures, AsteropJnjUites {Calamocladtis) and Annnlaria-. 

 probably being their foliage. 



Lycopods are also very numerous, and are represented by many 

 important genera — Lycopodites, Zepidodendron, LepidopMoios, 

 Bothrodendron, and Sigillaria, with their rhizomes Stigmaria and 

 Stigmariopsis. These genera contributed largely to the formation 

 of Coal. 



The genus Sphenophyllum was also frequent during Coal-measure 

 times, and forms a type of vegetation essentially distinct from any 

 existing group. 



The Gymnosperms are represented by Cordaites, Conifera), and 

 Cycads. 



The Cordaites had tree-like trunks and long yucca-like leaves. 

 They are plentiful in tlie Coal-measures, and, like the arborescent 

 lycopods, must have been a prominent feature in a Carboniferous 

 forest scene. 



The Conifera^, so far as I have seen, are only represented by 

 a single specimen of Walchia from the Upper Coal-measures ; and 

 though Cycads have been discovered in the Upper Coal-measures on 

 the Continent, I am not aware of any British species which can be 

 referred with certainty to this group. 



2. The Origin of Coal. By A. Strahan, M.A., F.G.S. 

 The deposition of the Coal-measures was due to the subsidence of 

 large portions of the earth's crust to a depth often amounting to 

 several thousand feet. The subsidence, being unequal, led to tlie 

 formation of coal-basins, parts of the margins of which are still 

 recognizable. That the intervening areas rose no less rapidly than 

 the basins sank is proved l>y the vast denudation suffered by the 

 earlier Palaeozoic rocks during the Carboniferous period. 



