of the Fossil Plants of the genus Sigillaria. 17 



dendron, I have little doubt that his description of the various impres- 

 sions of this fossil, under the name of Phytolithua cancellatus, would have 

 been in every respect complete.* 



With reference to ^igillariay let it be supposed that the diagrams 3, 4, 

 and 5, of Plate I. represent its cuticle under the various appearances, 

 and in the different states of division as just supposed, and it will be 

 seen in what manner several different surfaces may be afforded by a 

 single specimen. 



Let us suppose, that, in the third diagram, the cuticle a 6 of Sigillaria 

 is preserved in a fragment of slate, which is divided where the specimen 

 is imbedded, — that the cuticle adhered to that half or division marked 

 B, and that its original or external surface is exposed. Now it is evident, 

 that, in this case, there will be exposed on the other half of the slate A, 

 a surface which will differ from the former, in displaying the leaf scars 

 placed on wide furrows instead of ribs. Brongniart'st figures of Sigillaria 

 licvigafa (PL 143, fig. 1.) and Sig. Sauli (PI. 151), represent the original 

 surface of these species, while that of Sig. pyriformis (PI. 153, fig. 3) 

 shews merely an impression similar to that which ought to be seen on 

 the division A. 



With respect to the fourth diagram, let it be supposed, that, instead of 

 the external surface of the cuticle being exposed, we have the oppo- 

 site or internal one in this slate ; the surface of that division of the slate 

 marked A, will consequently be characterized with broad furrows, hav- 

 ing no leaf-scars, but merely vascular scars ; the latter will also be ex- 

 hibited on the other division marked B, but, instead of being on broad 

 furrows, they will be situated on ribs. The three North Biddick specimens 

 are in this latter state, an illustration of which may be seen by consult- 

 ing Lindley and Button's figure of Sigillaria reni/ormis (PL 57), while 

 the figure in the " Fossil Flora" of the so-called Sig. alternans (PL 56), 

 exhibits the inner surface of the cuticle, and consequently the appear- 

 ance displayed on that division marked A. t 



As regards the fifth diagram, it is to be supposed that the slate has 

 been divided in such a manner as to exhibit the surface of both layers a 

 and b of the cuticle, where they were in contact with each other, thereby 

 leaving a layer on each of the divisions A and B. The cases already 

 noticed have clearly afforded four different appearances ; the present one 



* American Philosophical Transactions, New Series, vol. 1, p. 280, &c. 



t All the references at present made to Brongniart's figures must be under- 

 stood to apply to his " Histoire des Vegetaux Fossiles," &c. 



I I am perfectly satisfied as to what is said in the text respecting Sigillaria 

 alternans being correct, for I have examined the specimen itself which Lindley 

 and Hutton have figured. In this note I cannot but acknowledge the kindness 

 and liberality of the latter gentleman, in allowing me the unreserved examination 

 of his invaluable collection of fossil plants, especially when it is considered, 

 that he was fully aware that my principal object was to support an opinion di- 

 rectly opposed to what he has advanced in the " Fossil Flora." 



VOL. XXXVI NO. LXXI. JAN. 1844. B 



