THE STORY OF THE EARTH. 



which the rocks occupy. First, Lake Cheviot in- 



Cheviot Hills with considerable thick- 



f volcanic rock of the kind named Por- 



phyrite or Andesite. Further north a great lake, 



ned Lake Caledonia, appears to have extended 



thward from the Grampians over the Firth of 



le into the North of Ireland. Third, the lake 



ot l red part of Argyleshire from Loch 



■■, and may have extended northward in the 

 line of the great glen. Further north still is the 

 old red sandstone region beyond the Grampians, 

 which includes Caithness and Sutherland, the Ork- 



- and Shetlands. 'Hie lake is named Lake 

 idie. It is tilled with conglomerates, red sand- 



e and grey flagstones, with occasional thin- 

 led limestones, sometimes bituminous in the 



upper part. 



In these beds there are many terrestrial plants, 



some conif( ind some, suchas Lepidodendron 



and Catamites y like those of the Coal, and similar 

 to the plants found m the upper Devonian rocks 

 of North Devon, probably derived from the land 

 to the north. Pterygotus, which had appeared in 



the marine Silurian beds, IS well known in the 

 old red sandstone Of Scotland, where it has been 



■ned by quarrymen "fossil seraphim." 



fishes air of extreme interest. First, there 

 is the remarkable extinct group of buckler-headed 

 ted by Pterichthys and 

 v, the more remai kab - of \v>- 



finned fishes termed Crossopterygidte, which are 

 nted at the present i\ay by Polypterus of the 

 \ e rhese fishes are < overed with bony 

 . and in< lud< it number of types such 



. ; : \\ hius y I 



to be in any S( 



