1520 C0RM0PHYTA. 



referred to Lycopodites, and it undoubtedly occurs in the Laramie 

 series of North America. 



With the Lepidodendrece we come to the first of the two extinct 

 families of the order, which contains gigantic forms characteristic of 

 the Upper Devonian and Carboniferous. These were tree-like Lyco- 

 pods with linear single-veined leaves, which leave rhomboidal scars, 

 often very prominent, at their point of attachment to the dichoto- 

 mously-branching stems. The fruit is in the form of scaly cones, 

 bearing macrospores and microspores, which may be either terminal 

 or lateral ; and the young branches have a pith-cavity, surrounded 

 by a layer of scalariform tissue, which sends out processes through 

 the thick bark to the leaves. As is the case with so many Palaeozoic 

 types, the different portions of these trees have received distinct 

 generic names. Thus the decorticated stems have been named 

 Knorria, fruiting branches, Halonia, and cones (fig. 1388) Lepi- 

 dostrobus, while at least some of the roots known as Stigmaria (fig. 

 1392) are referable to the present family. According to Sir J. W. 

 Dawson, there is considerable difference in the mode of growth of 

 the outer surface in different members of the family. 



" Thus in some species the areoles, at first close together, become, in 

 the process of the expansion of the stem, separated by intervening spaces 

 of bark in a perfectly regular manner ; so that in old stems, while widely 

 separated, they still retain their arrangement, while in young stems they 



are quite close to one another. This is 

 the case in Lepidodendron cornigattim. 

 In other species the leaf-scars or bases 

 increase in size in the old stems, still re- 

 taining their form and their continuity to 

 one another, as in L. imdulatiun, and 

 those forms which have large leaf-bases. 

 4 Pr°n a A L T dod wrnm In these species the continued vitality of 



the Carboniferous. One-third natural the bark IS shown by the occasional pro- 



size. (After Schimper.) duction of lateral strobiles [cones] on large 



branches, in the manner of the modern 

 Red-pine of America. In other species the areoles neither increase in 

 size nor become regularly separated by growth of the intervening" bark ; 

 but in old stems the bark splits into deep furrows, between which may 

 be seen portions still retaining the areoles in their original dimensions 

 and arrangement." 



The majority of the genera are common to Europe and the 

 United States, and some of them occur in other parts of the world, 

 as in the Palaeozoic of Australia, and the infra-Karoo series of South 

 Africa. The type genus Lepidodendron contains a number of species 

 with a most complex synonomy, and is characterised by its vertically 

 elongated leaf-scars and slender branches. According to the views 

 of Mr Kidston, the stems to which the name Ulodendron has been 

 applied are mainly referable to Lepidodendron, although others may 



