THE CARBONIFEROUS STSTEM. 



705 



the drawing of which this engraving is taken. These trunks were coated with a thin 

 layer of coal, their carbonised bark, the interior consisting of the shale in which they 

 were discovered. 



FOSSIL TREES on the Bolton and Manchester Railway : a, the trees ; b, stratification above the fossils ; c, d, e, thin beds of 



shale ; g, a seam of coal two feet thick. 



Sti 



marae. 



These extraordinary vegetable fossils are so called from their spotted stems, 

 as in the cut. They are known in almost every coal 

 mine, fragments occurring in almost every heap of shale 

 5s!j thrown out. A cylindrical stem, the surface marked with 

 tubercles or spots, with many horizontal branches or 

 leaves springing from it, the interior probably of a yield 

 ing fleshy substance, characterise this tribe of extinct 

 plants, which have now no living analogues. They are 

 supposed to have been aquatics, occupying swamps or 

 shallow lakes, attaining a considerable magnitude, the 

 stems varying in diameter from a few inches to several 



Stigmaria ficoides. fpft 



Lepidodendra. This name, signifying scaly-tree, refers to the scaly appearance of the 

 plants thus indicated, which are among the common constituents of 

 the coal measures. The cut represents a portion of the stem of 

 one species ; but stems occur, of other species, invested with 

 leaves of simple structure and lanceolate shape. By some they 

 are viewed as analogous to the existing lycopodiaceous genus, or 

 tribe of club-mosses, but we have no living examples of this 

 tribe which attain a greater height than three feet, and they are 

 principally weak, diminutive plants, trailing on the ground, 

 while these fossil specimens exhibit an enormous size, rivalling 

 forest-trees in magnitude. In the Jarrow colliery, a specimen 

 was discovered, the stem of which was forty feet in length, and 

 thirteen feet in diameter at the base, dividing towards the 

 summit into fifteen or twenty branches. 



Calamites. These plants, characterised by a reedy structure, cylindrical, articulated 

 stems, constituted an important feature of the vegetation of the carboniferous era, as shown 

 by the abundance of their remains, and are usually considered to have formed the earliest 

 terrestrial flora, some obscure traces of them being found in the more ancient strata. 

 Thev are thought to be allied to the existing order of Equisetacece, or horse-tails, a 



J 2s 



