OE THE EOSSIL PLANTS OE THE COAL-MEASUEES. 
221 
M. Corda’s plants were obtained from the Bohemian coal-field. It is now probable that 
the remarkable group of the Schizseese is represented amongst our British Carboniferous 
ferns. 
The next plants to which I would call attention bring us to one of the most debatable 
and earnestly debated of all the problems which the study of the Coal-plants has sug- 
gested. They are the Coniferse, or, to employ a more comprehensive term, the Gymno- 
spermse. In his ‘ Prodrome d’un Histoire des Vegetaux Fossiles,’ published in 1828, 
M. Brongniart says of the Gymnospermous Phanerogams, “ Aucune plante du terrain 
houiller ne paroit se rapporter a cette classe, a moins que quelques-unes des plantes que 
nous avons placees parmi les Lycopodes ne fussent des Coniferes 
In 1838 Witham published his well-known memoir “ On the Internal Structure of 
Fossil Vegetables found in the Carboniferous and Oolitic Deposits of Great Britain.” 
In this he described a number of plants which he arranged in two genera, Pitus and 
Pinites. The former genus was one of his own institution f . The latter he adopted 
from the authors of the ‘ Fossil Flora of Great Britain,’ who, in their first volume (p. 9) 
figured and described portions of the celebrated Craigleith Tree under the name of 
Pinites Withami. Witham also inclined to the belief that his Anabatlira fulcherrima. 
was a plant of Coniferous affinities. I have already pointed out, in a previous memoir J, 
that this latter plant was undoubtedly a Diploxyloid Lejpidodendron. As to the 
remainder of Witham’s plants I have tried in vain to form an accurate conception of 
their true character. Unfortunately Witham was wholly ignorant of the distinction 
between two very different classes of markings seen on the surfaces of prosenchymatous 
fibres, cells, and vessels. He evidently confounded the reticulations, which are merely 
deposits within and in close union with the cell-wall, and which are mere modifications 
of true spiral tissues, and the disks seen in Conifers and Cycads, and which, as is now 
well known, are lenticular spaces connecting two contiguous fibres. Accurately made 
tangential sections, in which the true medullary rays are intersected at right angles to 
their course, also exhibit sections of these lenticular cavities, appearing like very delicate 
vertical lines of chain-work. Of this eminently characteristic difference between two 
varieties of structure Witham knew nothing, as is demonstrated by his typical, tangential 
sections of recent examples represented in Plate 2. figs. 3-6 & 9, in which no traces of 
these intervascular structures are shown. I have no doubt that some of his supposed 
Conifers belong to the groups of plants which I have described in my fourth memoir § 
under the names of Lyginodendron and Heterangium, which I believe to be Crypto- 
gamic genera ||, whilst others doubtless do belong to the group which palaeontologists 
* Log. cit. p. 175. f Log. cit. p. 38. 
t Phil. Trans. 1872, pp. 299 & 309. § Phil. Trans. 1873, p. 379 et seq. 
1| Even Lindley and Hutton had strong doubts respecting the coniferous character of Witham’s stem, which 
in their ‘Eossil Elora’ they designated Pinites Withami. They say, “Notwithstanding the great similarity between 
the transverse sections of this wood and those of recent Coniferse, and notwithstanding the total absence of 
duets in what seems to have been a tree having an exogenous structure, yet that as the very remarkable 
MDCCCLXXVII. 
2 I 
