72 



VESTIGES OF THE 



were some palms {flahellaria and nceggeratlila), besides 

 a few not distinctly assignable to any class. 



The dicotyledons of the coal are comparatively few, 

 though on the present surface they are the most 

 numerous sub-class. Besides some of doubtful affinity 

 {annularia, asterojyhyUites, kc), there were a few of 

 the pine family, which seem to have been the highest 

 class of trees of this era, and are only as yet found in 

 isolated cases, and in sandstone beds. The first dis- 

 covered lay in the Craigleith quarry, near Edinburgh, 

 and consisted of a stem about two feet thick, and forty- 

 seven feet in length. Others have since been found, 

 both in the same situation, and at Newcastle. Leaves 

 and fruit being wanting, an ingenious mode of detect- 

 ing the nature of these trees was hit upon by Mr. 

 Witham, of Lartington. Taking thin polished cross 

 slices of the stem, and subjecting them to the micro- 

 scope, he detected the structure of the wood to be that 

 of a cone-bearing tree, by the presence of certain '' reti- 

 culations" which distinguish that family, in addition to 

 the usual radiating and concentric lines. That particular 

 tree was concluded to be an araucaria, a species now 

 found in Norfolk Island, in the South Sea, and in a few 

 other remote situations. The coniferas of this era form 

 the dawn of dicotyledonous trees, of which they may be 

 said to be the simplest type, and to which, it has already 

 been noticed, the lepidodendra are a link fi-om the 

 monocotyledons. The concentric rings of the Craig- 

 leith and other coniferre of this era have been men- 

 tioned. It is interesting to find in these a record of 

 the changing seasons of those early ages, when as yet 

 there were no human beings to observe time or tide. 

 The rings are clearly traced; but it is observed that 



