33 
which a great many are recorded, that will eventually prove 
to be only different parts of the same plant. Out of a 
large number of specimens in the collection of this Society, 
it is very probable that only three species are included, the 
Sigillaria pachyderma, organum, and flexuosa, to which 
we may add catenulata, if really distinct, though I suspect 
it to be only a variety of pachyderma. It is worthy of 
remark that the state of perfection of the specimens depends 
very much upon the situation in which they are found; if 
in the coal or shale, they are crushed flat and prostrate, 
whilst if in the sandstone, generally erect, and retaining 
their columnar or round form. From the quarry at Altofts, 
near Wakefield, several fine specimens have been procured ; 
one of Sigillaria flexuosa, in the Museum of the Philo- 
sophical Society, measuring nearly nine feet in height, was 
presented many years since by the Rev. Samuel Sharp, 
Vicar of Wakefield. Of the next genus, Favularia, which 
is far less frequent than the former, we find specimens of 
Favularia tessellata at Low Moor, Barnsley, Elsecar, and 
Shelf. In the museum of this Society are also several 
portions of large stems from the coal strata, from eight 
inches to two feet in diameter, without any of the external 
markings which characterise Sigillaria or Favularia. 
Associated in the same group of plants with the two 
preceding, that is, as far as uncertainty of affinity is con- 
cerned, we have the genera Megaphyton, Bothrodendron, 
Ulodendron, Halonia, and Knorria, and from thence, pro- 
bably, we may pass to the genus Lepidodendron. As to 
the proper situation of most of these genera considerable 
doubt exists, as but little of their history or real nature is 
revealed to us, further than that they embraced some of the 
most gigantic and lovely vegetable forms of the primaeval 
earth, and that they reared their lofty and verdant summits 
over vast and untenanted forests, where human foot had 
vol. in. c 
