52 CARBONIGENOUS ERA. 



One discovered in the Craigleith quarry, near Edinburgh, con- 

 sisted of a stem about two feet thick, and forty seven feet in 

 length. Others were afterwards found, both in the same situ- 

 ation, and at Newcastle. Leaves and fruit being wanting, an 

 ingenious mode of detecting the nature of these trees was 

 devised by some naturalists residing in the northern capital. 1 

 Taking thin polished cross slices of the stem, and subjecting 

 them to the microscope, they detected the structure of the 

 wood to be that of a cone-bearing tree, by the presence of 

 certain " reticulations" which distinguish that family, in addi- 

 tion to the usual radiating and concentric lines. That parti- 

 cular tree was concluded to be an araucaria, a genus now found 

 in Norfolk Island, in the South Sea, and in a few other remote 

 situations. The conifers of this era may be said to form the 

 dawn of dicotyledonous trees, to which it has already been 

 noticed, the lepidodendra are a link from the monocotyledons. 

 The concentric rings of the Craigleith and other conifers of 

 this era have been mentioned. 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 and 

 tide. The rings are clearly traced ; but it is observed that 

 they are more slightly marked than is the case with their 

 family at the present day, as if the changes of temperature had 

 been within a narrower range. 



Such (if we are to be allowed to rest with negative evidence) 

 was the vegetation of the carbonigenous era, composed of forms 

 low in the botanical scale, mostly flowerless and fruitless, but 

 luxuriant and abundant beyond what the most favoured spots 

 on earth can now show. The rigidity of the leaves of its 

 plants, and the absence of fleshy fruits and farinaceous seeds, 

 unfitted it to afford nutriment to animals ; and, monotonous 

 in its forms, and destitute of brilliant colouring, its sward 

 probably unenlivened by any of the smaller flowering herbs, 

 its shades uncheered by the music of birds, it must have been 

 a sombre scene to a human visitant. But neither man nor 

 any other animals were then in existence to look for such uses 

 or such beauties in this vegetation. It was, however, serving 

 another equally important end, storing up mineral masses 

 which were in long subsequent ages to prove of the greatest 

 service to the human race, even to the extent of favouring the 

 progress of its civilization. 



1 See Witham on the Internal Structure of Fossil Vegetables, 1834. 



