of the Fossil Plants of the genus Sigillaria. 19 



that they are due to the arrangement in linear series of the elongated cells 

 composing the prosenchymatous tissue of this layer, and as such are to 

 be distinguished from the lines which are occasionally seen running 

 up the lateral parts of the ribs of some corticated specimens, which shew 

 the outer surface of the cuticle,* and which lines I look upon as having 

 a totally distinct origin, as resulting in fact from the horizontal exten- 

 sion of the stem. It is by means of these longitudinal stricB that I have 

 arrived at the conclusion, that Lindley and Button's figure of SigiUaria 

 flewuosa does not exhibit the original or external surface of the cuticle 

 of this so-called species. 



It has been previously remarked, that I have not met with any single 

 specimens of this fossil shewing different surfaces of the cuticle : it is 

 probable, however, that SigiUaria hexagona (Brong. PL 155) is in this 

 state ; the part shewing the leaf-scars with a well-defined border is ob- 

 viously the external surface of the plant, — that which shews these scars 

 with a less defined border, appears to be the external surface of the 

 inner layer of the cuticle, — and the one which exhibits this character of 

 the scars very obscurely, is probably the impression of the inner sur- 

 face of the same layer. That the last part alluded to does not exhibit 

 the matrix on which the specimen is preserved, worn down below the 

 impression which ought to result from the inner surface of the inner 

 layer of the cuticle, is, I think, fully proved by the longitudinal strice 

 thereon exposed being so strongly marked. I would also suggest that 

 the various appearances exhibited by the figures of SigiUaria Knorri 

 (Brong. PI. 156, fig. 3) may be similarly produced; 



In none of the descriptions of SigiUaria that have come under my 

 notice, is there any mention made of this plant possessing axillary buds. 

 That such constituted one of its characters can admit of little if any doubt, 

 after an examination of the outline t which is given in our plate of il- 

 lustrations, and which is & facsimile of one of the leaf-scars of a specimen 

 in the Newcastle Museum, resembling Brongniart's SigiUaria scuteUata, in 

 the width of its ribs and the distance of the scars from each other 

 What I wish to call attention to in this outline is the prominence c above 

 the margin of the leaf scar a, a character which is seen above the whole 

 of the scars exhibited in the specimen. t Now, their situation relatively 

 to the leaf-scars being the same as that of the axillary buds of Dicotyle- 

 dons, and their occurrence above all the scars of the specimen, is, I think, 

 equivalent to a demonstration that these prominences are the remains 

 of the axillary buds of the plant on which they are preserved. This 

 character, taken in connexion with what has been stated of the branching 



* Vide Brongniart's figure of SigiUaria reniformis. 



t Vide Plate I, figure 6 — a the vascular scar — b the triple series of vascular 

 scars — c the axillary bud. 



I I have observed similar prominences, though they are not so obvious, on some 

 other specimens of SigiUaria ,• but instead of being a little above the leaf scar, they 

 are in close contact with its superior margin, — a position which, it is evident, most 

 render it difficult to see them. 



