60 DESCRIPTION OF FOSSIL TREES DISCOVEBED 



Fig. 6. Transverse slice of a small portion of the most regular part of a 

 very large mass found in situ, in the upper lias, near Whitby. It is very 

 much disturbed by the intrusion of calcareous spar, as is represented in the 

 figure, which is of the natural size. 



Fig. 7. Portion of the same, magnified, shewing part of two concentric 

 layers and their junction. In the unaltered parts the structure is very 

 regular, but exhibits few traces of medullary rays, and these not continuous. 

 The meshes are about the size of those of our recent pines. 



Fig. 8. Another portion of the same, magnified in the same degree, ex- 

 hibiting the confused appearance resulting from the intervention of calca- 

 reous spar. 



Fig. 9. Portion of a transverse slice of a fossil tree from the Whitby 

 Lias, shewing part of two layers. In this tree the medullary rays are 

 very distinct, as are the concentric layers. 



Fig. 10. Portion of a transverse slice of another tree from the Whitby 

 Lias, exhibiting the same general arrangement, but with much larger 

 cellules. 



Fig. 11. Portion of a transverse slice of a fossil tree, from the grey lime- 

 stone, near Whitby. The tissue of this fossil is extremely distorted and 

 altered by the intervention of calcareous spar, the woody fibres being thrust 

 together in black masses. The portion represented is the most regidar, 

 many of the other parts being perfectly opaque. 



Fig. 12. Portion of a transverse slice of another fossil tree from the 

 Whitby Lias. This also is very much distorted and broken up ; but as 

 little can be learned from the exhibition of black and homogeneous masses, 

 a portion exhibiting the regular texture of the plant has been selected. 



With respect to the fossil trees of the lias generally, I have to observe, 

 that all of them which I have examined agree in the following characters. 

 Their tissue in the transverse sections corresponds precisely with that of our 

 Coniferce, and more especially of the genus Pinus. They have a cellular 

 axis or pith, distinctly marked layers of woody tissue, and medullary rays. 

 It is probable enough that several of the trees, of portions of which I have 

 given representations, may be specifically distinct. In particular, those re- 



