1846.] BUNBURY ON STIGMARIA AND SIGILLARIA. 137 



such anomalies ; but every new fact recorded by skilful observers, 

 and bearing on a question of this kind, like that now communicated 

 by Mr. Dawson, is of great value. 



Whatever may be the case with regard to the Lancashire plant, 

 I see no proof, either in Mr. Dawson's specimens, or in his drawing 

 or description, that the fossil tree described by him was a Sigillaria, 

 I can find no trace eiiher of the regular flutings, or of the well-de- 

 fined leaf-scars, characteristic of that genus. If indeed the Sigil- 

 lariae were Dicotyledonous trees, having the ordinary Exogenous 

 mode of growth, it is clear that these superficial markings would be 

 obliterated by the increase of the stem in diameter, and would dis- 

 appear from the older parts of it, as happens in the Pines and Firs. 

 But M. Adolphe Brongniart expressly states that the Sigillariae pre- 

 sent the same appearances, the same furrows and leaf-scars, in the 

 lower parts of their stems as in the upper, and do not appear to have 

 increased in diameter by successive additions to the exterior, after 

 the manner of Exogens. It was partly on this ground, indeed, that 

 he originally maintained that they could not be Dicotyledonous 

 trees, but were of the nature of arborescent Ferns ; and even after 

 the examination of a specimen showing internal structure had in- 

 duced him to admit that they belonged to the Exogenous class, 

 he still dwelt on this peculiarity as removing them from the gene- 

 rality of plants of that class, and bringing them near to the Cycadeae. 

 In the figure which he has given of the base of a stem of Sigillaria* 

 found at Anzin, we see in fact the furrows and vascular scars repre- 

 sented as very distinct and perfectly regular. It is possible that the 

 various plants comprehended under the name of Sigillaria may differ 

 in this respect ; if not, we must admit that the Stigmariae described 

 by Mr. Dawson, though they might be roots, were not the roots of a 

 Sigillaria. 



Supposing it proved that the fossil called Stigmaria was really the 

 root of a tree, (and although the question cannot yet be considered 

 as definitively settled, I think that the positive and independent 

 statements of two such experienced observers as Mr. Binney and 

 Mr. Dawson give very great support to that opinion,) supposing this 

 proved, there still remain some obscurities to be cleared up in regard 

 to this singular production. In particular, what can be the nature 

 of that strange dome-shaped centre, figured in the * Fossil Flora,' 

 vol. i. t. 31, and vol. ii. pref. p. xiii? Is it the base or stool of a 

 trunk broken off near the root ? The figure given in the preface to 

 the second volume of the above-quoted work does not ill agree with 

 this supposition ; and it is possible that the " wrinkled appearance, 

 with indistinct circular spots," which the upper surface is there said 

 to have exhibited, may have been deceptive or accidental. Dr. 

 Lindley, who seems to have been the first to hintf that Stigmaria 

 might possibly be the root of Sigillaria, compares the dome-like 

 centre and radiating arms of Stigmaria with the roots and base of tiio 



* Hist, dcs V('g. Foss. vol. i. t. IGO. 



t Penny Cyclopjcdia, art. Coal Plants, published 1837. 



