in the Neighbourhood of Edinburgh. 173 



rence of character which it will be found to exhibit when com- 

 pared with the common mountain limestone of geologists. 



SECTION III — THE FOSSIL FLORA OF THE LIMESTONE. 



The vegetable matter which is diffused through the lime- 

 stone of Burdiehouse forms a peculiar feature of its character. 

 In some parts of the bed, more particularly in its higher seams, 

 carbonized matter appears in such an extraordinary quantity, as 

 to impart to the limestone a dark bituminous appearance. In 

 other sites, however, where such matter is less abundant, the rock 

 retains its prevailing bluish-grey or brown colour. 



Amidst this carbonaceous diffusion, which must have resulted 

 from vegetable matter in a decayed and pulverulent form, a pro- 

 fusion of fossil plants, analogous to those of tropical climates, ap- 

 pears encased in the rock in the most perfect state of preservation 

 imaginable. It is, however, much to be doubted if this vast as- 

 semblage admit of much variety among them, at least in propor- 

 tion to the immense mass accumulated. 



The plant which occurs in the greatest abundance is the 

 fern to which the name of Sphenopteris affinis has been recently 

 given. It is described by Messrs Lindley and Hutton, as hav- 

 ing a leaf which is bipinnate, the leaflets being deeply pinnatifid 

 into five segments, each of which is divided into from three to 

 five linear obtuse segments, which are broadest at the upper end, 

 and which are marked with from one to three parallel veins. 

 (Fossil Flora of Great Britain, plate 45.) 



This beautiful and delicate fern derives its chief interest from 

 prevailing in the deepest seated beds belonging to the carboni- 

 ferous group of the south of Scotland. In tracing the succession 

 of strata superimposed upon the transition schist of Cove in Ber- 

 wickshire, the first plant, which, in developing itself, breaks the 

 continuity of a long suite of previously formed sandstones, little 

 varying, and unfossiliferous in their geological character, is the 

 Sphenopteris affinis. I found it here enshrined in a bed of bitu- 



