On the Fossil Plants of the Coal-measures. 269 



the stem as the centre of a petiole ; but before it does so a new 

 one is detached from the opposite side of the central cylinder, 

 which, in turn, imitates its predecessor. Besides these primary 

 bundles, numerous secondary smaller ones are detached, some- 

 times from the central cylinder, sometimes from near the bases 

 of the petiolar bundles ; these probably supplied rootlets. The 

 author points out that this fern, along with the Amichoropteris 

 Decaisnii and the Zygopteris Brongniarti of M. Eenault, constitute 

 a group of ferns having a very distinct type of stem-structure 

 different from what is found in the rhizomes of recent ferns, and 

 which approximates to the lower Lepidodendroid stems as repre- 

 sented by L. Harcourtii. Two kinds of sporangia of ferns are 

 described. One of these has a perfectly vertical annulus, such 

 as is common amongst the Polypodiacese. A second has a large, 

 horizontal, subterminal annulus, approaching closely to the form 

 seen in the recent Gleicheniacese and Schiza^acese, especially re- 

 sembling the latter type. Both these sporangia contained spores ; 

 in the first mentioned these were numerous and small ; in the 

 latter they are fewer in number, but of larger dimensions. The 

 Gymnospermous stems of the Coal-measures are next examined. 

 The small branch of Dado.vylon from Coalbrook Dale, described by 

 the author many years ago in the Transactions of the Manchester 

 Literary and Philosophical Society, is first restudied. Its pith is 

 Sterubergian ; its ligneous zone has a medullary sheath of barred 

 vessels, whilst its woody zone is composed of wedges of discigerous 

 fibres arranged exogenously and separated by mural medullary rays. 

 The disks of the fibres lack the central perforations seen in those 

 of recent conifers. The bark is exactly like that of a young shoot 

 of a Taxus, consisting of an inner liber, the tissues of which are 

 arranged compactly in lines running parallel to each other and to 

 the surface of the wood ; whilst the outer layer consists of large 

 parenchymatous cells, which in the living plant doubtless contained 

 chlorophyl. It appears to correspond to the phelloderm, no true 

 phellein layer being present. Other branches, especially from the 

 Ganister beds near Oldham and Halifax, are also described. Many 

 of these are of much larger size, but all have Sterubergian piths, 

 with the exception of one in which the parenchymatous medulla 

 is not disciform, but like that of living conifers. The chief pecu- 

 liarity in the majority of these latter fossil branches and twigs is 

 that they give off small twin Avascular bundles from the innermost 

 surface of the ligneous cylinder. These pass outwards side by 

 side through the smaller branches, but can only be traced in the 

 innermost portions of the larger ones ; hence it is probable that 

 they either supplied leaves arranged in pairs (not distichously), or 

 that they went to a binerved leaf, the latter being most likely 

 to have been their real destination. The bark is rarely preserved 

 in these larger specimens from the Ganister ironstones, in which 

 they are associated vath myriads of Goniatites, an indication that 

 they have been drifted from a distance and long exposed to water 

 — conditions very different from those characterizing the oi-igin of 

 ihe coal in which most of the Oldham plants have been obtained. 



