104 THE STORY OF THE EARTH AND MAN. 



tic club-mosses, which were developed to still greater 

 dimensions in the coal period. Near these we may 

 see a still more curious tree, more erect in its growth, 

 with rounded and somewhat rigid leaves and cones 

 of different form, and with huge cable-like roots, 

 penetrating the mud, and pitted with the marks of 

 long rootlets. This is Cyclostigma, a plant near to 

 the Lepidodendron, but distinct, and peculiar to the 

 Devonian. Some of its species attain to the dimen- 

 sions of considerable trees ; others are small and 

 shrubby. Another small tree, somewhat like the 

 others, but with very long shaggy leaves, and its 

 bark curiously marked with regular diamond-shaped 

 scars, is the Leptophleum. All these plants are pro- 

 bably allied to our modern club-mosses, which are, 

 however, also represented by some low and creeping 

 species cleaving to the ground. A little further, and 

 we reach a dense clump of Sigillarite, with tall sparsely 

 forking stems, and ribbed with ridges holding rows 

 of leaf-scars a group of plants which we shall have 

 further occasion to notice in the coal formation ; and 

 here is an extensive jungle of Calamites, gigantic 

 and overgrown mares' -tails, allies of the modern 

 equisetums. 



Amidst these trees, every open glade is filled with 

 delicate ferns of marvellous grace and beauty; and 

 here and there a tree-fern rears its head, crowned 

 with its spreading and graceful leaves, and its trunk 

 clad with a shaggy mass of aerial roots an ol<l 

 botanical device, used in these ancient times, as well 



