308 . 
fragment of Sigillaria being fonnd which, if it had ever been 
in the sandstone with the roots, onght to have been as care- 
fully preserved. We have, however, very fine slabs of 
Lepidodendron orbovatum, and, also, very large stems, with 
a slightly longitudinally corrugated surface, or a somewhat 
pustular appearance, either of which is just as likely to have 
arisen from the dome- shaped, radiated roots referred to, as 
Sigillaria. I suspect the difference in external configuration 
of some specimens of fossil plants in other respects nearly 
related is mainly depending upon the simple circumstance, 
whether the impression preserved is that of the external or 
internal surface of the cortical envelope, which will differ 
materially, for notwithstanding the labours of Brongniart, 
Lindley, Hutton, Hooker, and others, our knowledge of fossil 
botany is still very imperfect ; and it is not improbable that, 
as greater facilities are afforded for examining extensive 
collections, containing specimens in different states of preser- 
vation and at various periods of growth, it will be found 
necessary to reduce the number of genera and species at 
present recognised. The probability is, evidence may thus be 
obtained that several supposed distinct species are, in reality, 
only different portions of the same plant. An instance of 
which has recently been presented to the Museum of 
the Leeds Philosophical and Literary Society, which con- 
sists of a specimen of Catamites, with the upper portion 
having the character of Approximate, and the lower that 
of Cannseformis. 
