Fossil wood, described under the name Cupressinoxylon, has been recorded from several Mesozoic horizons in Europe and elsewhere, but this term has been employed in a wide sense as a designation for a type of structure met with not only in the Cupressineae, but in members of other families of Coniferae.
Other characters, however, prove that the Cordaiteae were remote from that family, and the name Araucarioxylon is best Limited to wood from later horizons, where a near relationship to Araucarieae is more probable.'
Any detailed account of the horizons of Carboniferous plants would carry us much too far.
Many British species and associations of genera and species, occurring on corresponding horizons to those on which they are found in Britain, have been met with in the graptolite-bearing Lower Palaeozoic formations of other parts of Europe, in America, Australia, New Zealand :and elsewhere.
The Russian Altai is composed mainly of mica and chlorite schists and slates, together with beds of limestone, and in the higher horizons Devonian and Carboniferous fossils occur in many places.