72 THE WESTPHALIA^, ETC. OF EAST GLAAIOEGAV. ~Yol. kxvii, 



EXPLAXATIOX OF PLATE n. 



General graph showing the distribution of plants in relation to time and 

 space in the "Westphalian Series, and in the lower part of the Staf- 

 fordian Series, of Clydach Yale and Gilfach Goch (Glamorgan). 



Discrssiox. 



Prof. P. F. Kexdall said that the Author had devised and 

 applied a novel and valuable method of research into the plant- 

 distiibution in the Coal Measui-es, and he was to he congratulated 

 on the accomplishment of an arduous task. 



He enquired whether the samples of shale examined constituted 

 the immediate roof of the seams, that was, the layers within a 

 few inches of the seam. The speaker believed that these would 

 in many cases yield evidence of the last ' crop * that contributed to 

 the grovrins: seam. 



In the "NYestphalian measures of Yorkshire the roofs of many 

 seams — for example, the Silkstone. Middleton Main, Haigh Moor, 

 and Parkgate — c-ontained prosti-ate stems of SigiUaria and ' pot- 

 holes * ; the casts of hollow tree-stumps were also of fi-equent 

 occurrence in similar positions. The speaker had never observed 

 Lepidodendroid ti-uuks along with them : on the other hand, the 

 roof of the Barnsley Bed was renowned as a source of line fernlike 

 plants. 



With regard to the Author's eoujeetiu'es respecting the habitat of 

 the different types, he remarked that, whereas Lycopods commonly, 

 and Calamites more rarely, were to be found rooted in the position 

 of growth, he could not recall a single instance in which unequivocal 

 evidence of femlike plants in the attitude of growth had come 

 under his observation. 



He enquii'ed whether the Author had made any examination of 

 thin sections of the coal-seams. This method of study would throw 

 light upon the question whether the plants found in the inter- 

 vening measures were similar to those composing the coal. The 

 speaker had been enabled, by the generosity of the owners of 

 collieries in Yorkshire, to obtain a unique suite of thin sections, 

 exhibiting the whole thickness from floor to roof of the Barnsley 

 Bed, from six pits, and he had hopes of ultimately covering the 

 entire field from Leeds to Xottingham. 



It was to be hoped that the Author's methods might be applied 

 over a yet wider area in South Wales, in order to see whether his 

 results gave any support to the view that the b-ansition from bi- 

 tuminous coal to anthracite was in any way related to the ecology 

 of the constituent flora. 



The occui-rence of coal-pebbles at the base of the Staff ordian 

 measm*es was a fact of great interest : and, from an inspection of 

 the specimens exhibited, he quite agreed that they had not been in 

 the condition of peat when they were formed. It had been argued, 

 in other instances, that the mineralization must have been com- 

 pleted prior to the enclosm^e of the pebbles in the smTounding 



