108 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



selaginoides, figured by Messi's. Lindley and Hutton in their * Fossil 

 Flora,' vol. i. fig. 12 ; but the depression in the scar on their speci- 

 men is not so marked as in mine. 



In the middle of the large cylinder last described is a smaller one, 

 of about ^th of an inch in diameter. This is composed of large 

 hexagonal vessels, of irregular sizes (a a), placed one beside the other, 

 without order, but becoming smaller as they approach the circumfer- 

 ence, all having their sides barred with transverse strise, and some of 

 the smaller ones (a' a') being divided at short intervals by horizontal 

 and oblique partitions. The outside of this inner cylinder* (b h) is 

 composed of hexagonal vessels barred with transverse striae, of about 

 -i-th of the diameter of those contained in the centre, arranged in 

 radiating series of a wedge-shape, and divided by meduUary rays or 

 vessels very finely barred (c c), as in the vascular cylinders of Sigil- 

 laria and Stiymaria, respectively described by Brongniart and 

 Hooker. Around, and placed next to, the cylinder are a number of 

 round bundles of fine vascular tissue (del), some of which are oppo- 

 site to the medullary rays or vessels, and others apparently away 

 from them near the wedges of the wood. These bundles seem to 

 be connected with the vessels which supply the leaves, but cannot 

 be well traced to the medullary rays in aU cases. It is probable 

 they may be sections of vessels passing from the medullary rays 

 or vessels to the leaves. They are evidently the same vessels as 

 are figured by Messrs, Lindley and Hutton (' Fossil Flora,' vol. ii. 

 pi. 99. fig.l), and also resemble the vessels described by Brongniart as 

 occurring on the outside of the woody cylinder in Sigillaria elegans. 

 On the external portion of the outer radiating cylinder of the specimen 

 similar vessels can be distinctly traced into the projecting scars from 

 whence the leaves arise. 



Next occurs a space of about y^^ths of an inch {ee), in which the 

 tissue has for the most part disappeared and been replaced by mine- 

 ral matter; but it seems to have been composed of delicate cellular 

 tissue, which was traversed by bundles of vessels leading from the 

 axis to the leaves. Then comes a zone of coarse cellular tissue (//) 

 which gradually passes into small elongated utricles, of hexagonal 

 form, and arranged in radiating series, which probably formed the 

 inner bark. These, in their turn, pass into a black carbonaceous 

 matter Qi h), the remains of the outer bark of the tree. The vessels 

 traversing the external cylinder are of the same character as those 

 traversing the internal one, except that they are of much greater 

 size, each of the latter being probably composed of two or more of 

 the former, as Dr. Hooker describes in Sigillaria f. A transverse 

 section of the specimen No. 1 is similar to the same section of Sigil- 

 laria elegam, with this exception, namely, that the inner lunette- 

 shaped bundles of vessels found within and next to the woody cy- 

 linder in M. BrongTiiart's specimen fill the whole of the central axis in 



* In this specimen, by some cause, a portion of the inner cylinder has been 

 destroyed, either by the section not being cut true, or by a part of the woody 

 cyHnder having been destroyed in calcification. 



t Memoirs of the Geological Survey of Great Britain, vol. i. part ii. p. 436. 



