27 
the neighbourhood of Wentworth and Sheffield ; verti- 
cillatus from Pontefract; and varians from Gildersome. 
Brongniart mentions, and figures a fragment from, a 
large species of Calamite whose locality was unknown, 
measuring about a foot in diameter, under the name of 
gigas. In the collection of this Society is also the lower 
portion of a very large specimen, which agrees with his 
figure in appearance, but is at least three feet in its 
longest diameter ; this, however, is partially owing to the 
plant having suffered lateral compression, exclusive of 
which, it could not have been less than two feet. On 
account of its extraordinary size I should have considered 
this specimen, without hesitation, a Sigillaria, but the scars 
or punctures which are so characteristic of this genus are, 
in this specimen, absent, the stem presenting nothing but 
the parallel furrows. In Brongniart's figure, and also our 
own, the specimen is too short to exhibit satisfactorily the 
transverse septa or joint, so distinguishing a feature in the 
genus Calamites; but an indistinct approach towards this 
structure is partially observable on both. If this specimen 
is not a Calamite, what is it? as the lower portion of all the 
stems of Sigillaria which I have seen were not without the 
scars or punctures, and the commencement of the roots of 
Stigmaria have not the parallel ribs, but a striated appear- 
ance. 
The true Ferns, at which we are now arrived, are, as I 
have before observed, the most abundant of all plants in 
the coal formation, almost every yard of the shale being 
more or less filled with their impressions. The fructifica- 
tion, however, which is so striking a feature in this class 
of plants, is almost universally destroyed by the long sub- 
mersion, or other causes to which they have been subjected, 
so tljat the classification adopted for recent ferns cannot 
be employed for the fossil species, in lieu of which the 
