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E UR OPEA N F URNS. 
that which is found in the stems of Monocotyledons ; for in both we have the vascular bundles 
which go to the appendages existing in the parenchymatous axis, and passing out independently 
of any closed cylinder. The permanent vascular plates of the circumference of the stem in the 
extinct forms are without any analogue in the monocotyledonous stems. 
The proportion of ferns to the other groups of plants is very different in the 
Secondary rocks to what we have found in those of Palaeozoic age. The relative paucity 
of other plants in the older rocks may be due to the want of favourable conditions for their 
preservation. No phanerogamous plants have yet been discovered in the C.oal measures in the 
localities where they grew. They are known either by stems or fruits which have been 
transported by running water. No foliage has yet been detected. In the Triassic rocks 
we find foliage as well as wood and fruits, and these evidences of Gymnosperms together 
with the remains of Monocotyledons increase, while the number of ferns decrease. About 
forty species have been described from the Trias, several of which were arborescent. Their 
arborescent allies of the Coal period belonging to Lycopods and Equisetums have given 
place to forms more nearly approaching those of the present day. 
In the Oolite the ferns increase in number, being represented by about one hundred 
and fifty species. Among these are found forms whose affinities with existing species 
cannot be determined, like the petiolate, flabelliform, and divided fronds from the Yorkshire 
Oolites, placed in the genus Baiera ; or the coriaceous cycad-like fronds of Nilssonia from 
the same beds, the position of which among ferns has been established by the discovery 
of fruiting specimens showing small round sori scattered over the back of the frond; or, 
still more, the Liassic group of plants placed in the genus Thinnfeldia , which Ettingshausen 
referred to Conifercz because of their resemblance to the Australian genus Phyllocladus, while 
Schenk considered them to be Cycadean and allied to the abnormal genus Stangeria , from 
Natal. 
The Cretaceous beds do not supply much evidence of the land flora of the period when 
they were being deposited. A dozen species of ferns have been described from Greenland 
in beds which are of Lower Cretaceous age, and about fifty species from the richly 
fossiliferous beds near Aix-la-Chapelle, that are considered to be on the horizon of the Upper 
Greensand. The ferns at least suggest a newer formation, being very closely related to, 
if they are not in many cases identical with, species found in the Eocene beds of the 
south of England. 
The ferns found in Tertiary strata agree very closely with existing generic types ; 
and though it may not be always possible to refer them with certainty to a particular 
genus, from the absence of the fructification, no characteristics have been observed which 
would justify their separation into distinct genera, at least on the grounds on which 
genera are established among recent ferns. The Tertiary strata of the south of England 
have yielded a considerable number of species. They have their affinities with ferns of 
subtropical regions, and testify like the other plants and animals of these rocks to a 
much warmer temperature than we now enjoy. The only form found in Tertiary rocks that 
is related to a species now living in Britain is the stem of a Royal fern found on the 
beach at Herne Bay, and derived no doubt from the Eocene beds there. The stem was 
beautifully preserved, exhibiting the most minute details of its structure, which agrees with 
the stem of Osmunda recalls, though the plant was most probably considerably larger. 
