36 DESCRIPTION OF FOSSIL TREES DISCOVERED 



The only differences to be observed between the texture of the branch 

 in question, and the other fossils of the same quarry, is, that, in the trans- 

 verse sections, there are distinct traces of concentric lines, and in the sec- 

 tions parallel to the bark, the medullary rays are more numerous, and more 

 uniformly of about four series of cellules. As to the pith, I am unable to 

 say what its size may be in the great trunks. The branch of 1831 is there- 

 fore probably of the same species as the rest, although it may be allowed to 

 retain the name imposed upon it, and be considered as a doubtful species, 

 until the examination of the pith of the other fossils decide the question. 



We now return to the fossils found at Lennel Braes, on the Tweed, 

 which have been partially described. In addition to the transverse sections 

 of these plants figured in Plate IV, it is necessary to present other two, 

 which will be seen in Plate VII. 



Fig. 11. Represents, of the natural size, the pith, as mentioned at p. 27, 

 of extraordinary magnitude, encircled by the woody tissue, in which are seen 

 medullary rays radiating in the usual manner. The central part of the pith 

 is broken up by crystallizations of calcareous spar, and the woody tissue by 

 fissures filled with the same substance. This plant is obviously more de- 

 serving of the name of medullar is than the Craigleith branch just de- 

 scribed. 



Fig. 12. Is a highly magnified portion of the same section, not far 

 from the margin of the pith. Two medullary rays are seen, together with 

 a few apertures of the elongated cellules. It seems somewhat remarkable 

 that the tissue intervening between these cellules, and even the interior of 

 the cellules themselves, in some parts, are filled with very minute reticula- 

 tions. In other respects, however, the tissue resembles that of the Coni- 

 ferae, and of the Craigleith fossils. 



Fig. 9- Is a longitudinal section parallel to the medullary rays. In 

 this direction, the tissue is much broken up and confused, so that only in 

 one minute space I have been able to detect its real nature. The elon- 

 gated cells are there seen, as represented to contain two series of roundish 



