THE CARBONIFEROUS. Co 



Parsboro', aiul by myself" at the Joggins, and referred to in Acadian 

 Geology. These smaller footprints, showing marks of three toes, 

 and ill more distinct impressions of four or five, I have con- 

 jectured may have been i)rudiiced by Labyrinthodonts of the type of 

 Dendrcrpeton. 



Origin of Coal. 



The readers of recent English popular works on geology will have 

 observed the statement reiterated, that a large proportion of the 

 material of the great beds of bituminous coal is composed of the 

 spore-cases of lycopodiaceous plants — a statement quite contrary to 

 that resulting from my microscopical examinations of the coal of more 

 than eighty Coal-beds in Nova Scotia and Cape Breton, as stated in 

 Acadian Geology (page 463), and more fully in my memoir of 1858 

 on the Structures in Coal,* and that of 18G6 on the Conditions 

 of Accumulation of Coal.-j- The reason of this mistake is that an 

 eminent English naturalist, happening to find in certain specimens of 

 English coal a great quantity of remains of spores and spore-cases, 

 though even in his specimens they constitute only a small portion of 

 the mass, and being apparently unacquainted with what others had 

 done in this field, wrote a popular article for the Contemporary 

 Review, in which he extended an isolated and exceptional fact to all 

 coals, and placed this supposed origin of coal in a light so brilliant 

 and attractive that he has been followed by many recent writers. 

 The foct is, as stated in Acadian Geology, that trunks of Sigillarice 

 and similar trees constitute a great part of the denser portion of the 

 coal, and that the cortical tissues of these rather than the wood remain 

 as coal. But cortical or epidermal tissues in general, whether those 

 of spore-cases or other parts of plants, are those which from their 

 resistance to water-soakage and to decay, and from their highly 

 carbonaceous character, are best suited to the production of coal. In 

 point of fact, spore-cases, though often abundantly present, constitute 

 only an infinitesimal jiart of the matter of the great Coal-beds. In an 

 article in Silliman's Journal, which appeared shortly after that above 

 referred to, I endeavoured to correct this error, though ap})arently 

 Avithout effect in so far as the majority of British geological writers 

 are concerned. From this article I may quote the following passages, 

 as it is of importance in theoretical geology that such mistakes, 

 involving as they do the whole theory of coal accumulation, should 

 not continue to pass current. The early part of the paper is occupied 



■'^' JouriKil Geol. Society, vol. xv. f I)t!<l, vol. xxii. 



