202 STUDIES IN FOSSIL BOTANY 



ordinary mode of preservation in which one of the 

 species, B. punctatum, occurs. At Tovarkovo, in the 

 province of Toula, in Central Russia, beds of a peculiar 

 kind of coal, called leaf-coal or paper-coal, have long 

 been known. The seams are about 8 inches thick, and 

 lie near the surface of the ground, only covered by 

 sand. The so-called coal has all the appearance of 

 a bed of excessively thin dead leaves, intermixed only 

 with structureless organic matter of the nature of 

 humic acid. The leafy films, on investigation, have 

 proved to consist entirely of layers of cuticle, belonging 

 to the stems of ancient plants, from which all other 

 tissues had rotted away, ages before. The cuticles 

 are perfectly fresh and pliable, and not in any way 

 fossilised, although geologists are agreed that the bed 

 (which covers an area of many square miles) belongs 

 to the Carboniferous Limestone horizon, in the lower 

 part of the Carboniferous formation. The cuticle is 

 in some cases complete, corresponding to the whole 

 circumference of the stem which it once enclosed ; it 

 is perforated by numerous small round holes, regularly 

 disposed, and corresponding in arrangement with the 

 leaf-traces of a Bothrodendron. The cuticularisation 

 had evidently extended to a portion of the vertical 

 cell-walls abutting on the outer skin, for the network 

 of cells is marked out with perfect clearness on the 

 inner surface of the cuticle. Irregular borings, which 

 occur here and there in the membrane, were attri- 

 buted by M. Renault to the activity of Palaeozoic 

 Bacteria. 



The cuticles, when freed from the formless organic 

 matter adhering to them, are of a light brown colour ; 



