28 DESCRIPTION OF FOSSIL TREES DISCOVERED 



length of this trunk was 36 feet, and its diameter at the hase 3 feet. It lay 

 in a nearly horizontal position, corresponding with that of the stratum of 

 hard white sandstone, in which it was imbedded. Externally, it was marked 

 with irregular longitudinal grooves and prominences, and was encased in a 

 layer of coaly matter, being probably the altered remains of the bark. No 

 branches were observed. Internally, it exhibited in some places an irregu- 

 lar fibrous or fascicular structure, of a dark grey colour, with reticulations of 

 carbonaceous matter. The cracks and fissures were filled with calcareous 

 spar, and the irregular cavities which it presented were lined by crystals of 

 pearl-spar. 



An analysis of a portion of this plant afforded the following result ; 



Carbonate of Lime, 60 



Oxide of Iron, 18 



Alumina, 10 



Carbonaceous matter, 9 



Loss, . . . . • 3 



100 



In Plate IV. are seen representations of portions of transverse slices of 

 this stem. 



Fig. 8. Portion of the Craigleith tree of 1826, shewing the regular 

 woody texture, separated by medullary rays ; magnified about forty-five 

 times. 



Fig. 9. Another portion of the same, magnified in the same degree, in 

 which the woody texture and medullary rays are more or less distorted. 



Fig. 10. A portion of the same tree, magnified about fifty-five times, 

 very regular in its texture, and shewing a medullary ray irregularly lace- 

 rated. 



Figs. 11. and 12. Portions of the same, shewing various degrees of se- 

 paration of the woody texture or indurated or elongated cellules, their walls 

 being very thin in Fig. 11. and very thick in Fig. 12. 



The absence of lines of separation of the woody layers, is the only cir- 

 cumstance in which these figures differ from those of transverse sections of 



