Ill] PERMIAN PERIOD. 45- 



part of the Earth's crust. In the neighbourhood of London^ 

 Dover, and other places we have Tertiary and Mesozoic strata 

 forming the surface of the country, but below these comparatively 

 recent formations, the sinking of deep wells and other borings 

 have proved the existence of a ridge of Palaeozoic rocks 

 stretching from the South Wales Coal-field through the South- 

 east of England to northern France, Belgium and Westphalia. 

 It is from rocks forming part of this old ridge that characteristic 

 Coal-Measure plants have been obtained from the Dover boring. 

 In Fig. 5 is shown an almost complete pinnule of Neuropteris 

 Scheuchzeri Hoffm., a well-known fern, marking a definite 

 horizon of Upper Carboniferous rocks ^ The small hairs on 

 the pinnules, shown in the figure as fine lines lying more or 

 less parallel to the midrib and across the lateral veins, are a 

 characteristic feature of this species. 



Fig. 5. 



Imperfect pinnule of Neuropteris Scheuchzeri Hoffm., showing the character- 

 istic hairs as fine lines traversing the lateral veins. From a specimen obtained 

 from the Dover boring and now in the British Museum. Nat. size. 



YII. Permian. 



Reference has already been made to the earth-foldings 

 which marked the close of Carboniferous times; "the open 

 Mediterranean sea of the Carboniferous period in Europe was 

 converted into a large inland sea, like the Caspian of the 

 present day, surrounded by a rocky and hilly continent, on 

 which grew trees and plants of various kindsl" In parts of 



1 Vide Zeiller (92) for a list of species of Coal-Measure plants found in 

 the pieces of shale included in the core brought up by the borer. 



2 .Jukes-Browne (86), p. 252. 



