of the Fossil Plants of the genus Sigillaria. 75 



remembered, has been proved to be merely the indurated mud which 

 occupied the hollow or under surface of a root, — there are actually dis- 

 played two strongly-marked ridges, crossing each other precisely under 

 the same circumstances as the furrows of the aforementioned Sigillarias. 

 It will doubtlessly occur to many, that these furrows are analogous to 

 those usually seen on the under surface of the branches of ^tigmaria, 

 and that they have been produced in the same manner, — that is, by the 

 settling down of the ligneo-vascular cylinder after the destruction of the- 

 enveloping and less enduring cellular tissue. According to this view, 

 the intersecting furrows on the fossil root-stocks, will have resulted 

 from the ligneo-vascular cylinder of the stem dividing itself into four 

 parts ; and these divisions striking off into the root-branches, at right 

 angles to each other : a circumstance of this kind, it is conceived, would 

 give rise to that appearance of crossing each other which the furrows 

 present. 



I cannot conclude the present inquiry more appropriately than by 

 quoting a portion of Mr N. Wood's description of the Killing worth Si- 

 gillaria, — observing, in the first place, that the specimen, which appears 

 to have been about 10 feet in height, was discovered with several others, 

 in a nearly vertical position, and evidently rooted in a thin bed of argillo- 

 bituminous shale, overlying a workable seam of coal : " The lower part 

 or base of the tree was about two feet in diameter, flattening out consider- 

 ably at the bottom ; this part was so much broken that it could not be 

 procured ; but the bed of it, with the roots proceeding from it, was most 

 clearly seen in situ. The roots could be traced for about four feet from 

 the stem, penetrating the shale ; but the compact nature of the shale pre- 

 vented us from obtaining specimens, when the thickness of the roots 

 diminished ; but they were seen running into the shale composed of the 

 same kind of sandstone, though a little more indurated, until they were 

 less than an inch thick. * * * * The roots were not numerous, 

 but ran into the shale quite parallel with the inclination of the beds, and 

 spread out from all the diflPerent sides of the fossil.''* To this account, 

 it is necessary to add, that the specimens themselves of the divided root 

 branch, and the stem, which are figured in Mr Wood's paper, are at 

 present in the Newcastle Museum : the root-branch is decidedly a Stig- 

 maria, and the stem appears to be a Sigillaria. 



Thus, bearing in mind that Siigmaria has been proved to have been a 

 root ; and, considering the tendency of the evidences latterly adduced, 

 it now seems to be all but demonstrated, that this fossil was the root of 

 Sigillaria, 



{To be concluded in our January Number.) 



* Transactions of the Natural History Society of Northumberland, Durham, 

 jmd Newcastle-upon-Tyne, Vol. i., p. 210. 



