74 Contributions towards Establishing the General Character 



the *' Fossil Flora/* (Vol. i.) is said to have had the whole of its under 

 surface '' distinctly covered with wrinkles, which, when attentively 

 examined, are seen to be caused by depressed semicircular spots, com- 

 pactly arranged in a spiral manner, in the centre of which is a roundish 

 scar, to which a fine coaly matter usually adheres :" further, the convex 

 specimen, described in the preface of the second volume, is stated to 

 exhibit " the same wrinkled appearance, with indistinct circular spots," 

 as the last. As I have only seen the dome-shaped specimen, I can, of 

 course, only speak with reference to it, and I shall do so with the view 

 of preventing the supposition arising, that the " indistinct circular spots" 

 are such as to shew, that the convexity of the last fossil, and the concavity 

 of the North Biddick Sigillaria, exhibit totally different characters. It 

 is necessary, however, to remark, in the first instance, that as the convex 

 specimen is merely an impression of the outer surface of the cuticle of a 

 root, it is obvious, a knowledge of the character which this surface dis- 

 plaj^ed would materially assist us in our immediate object. Influenced 

 by this consideration, I took a plaster cast of the crown of the speci- 

 men ; by this means I succeeded in obtaining an exact copy of the 

 surface of the cuticle, which copy displayed a character strikingly re- 

 sembling — though on a smaller scale — the elongated lozenge-shaped rifts 

 characteristic of the bark of some of our forest trees, especially the ash 

 (Fraxinus excelsior.) 



As to the scars — that is, such as have resulted from the falling off of the 

 fibrils, not a single one was visible ; they were, in fact, only seen where 

 the branches had left their impression on the channels. The absence of 

 the rifted character on the under surface of the root of the North Bid- 

 dick Sigillaria, and its presence on the same part of the root which pro- 

 duced the convex specimen, seems to be due simply to a difference of 

 age, and to a rifting of the cuticle of the last example, through an in- 

 crease of the tissues which this cuticle originally enclosed ,* at least, such 

 are the apparent causes of the disparity between the bark of old and 

 young individuals of the ash ; and there appears to be no reason why 

 the same causes have not operated in producing the like difference 

 noticed in the fossils. 



There yet remains another point to be mentioned in favour of Stig- 

 maria being the root of Sigillaria. As previously remarked, the charac- 

 ter which has just been concluded is only to be seen on the root-stock 

 of one of the North Biddick specimens. The root-stock of the other has 

 also been preserved separately ; but instead of its under surface dis- 

 playing any wrinkles, there are visible two strongly-marked furrows, 

 which cross each other in the centre, and at right angles, and which dis- 

 appear at the margin : this difference is probably due to both fossils 

 being preserved under different circumstances. I have observed similar 

 furrows on the under side of a root-stock of a stem — apparently of a Sigil- 

 laria, belonging to Wm. J. Charlton, Esq. of Hesleyside. Now, on ex- 

 amining the crown of the dome-shaped specimen, — which, it must be 



