146 ON THE FORMATION OF COAL v 



When I had the pleasure of seeing Principal 

 Dawson in London last summer, I showed him 

 my sections of coal, and begged him to re-examine 

 some of the American coals on his return to 

 Canada, with an eye to the presence of spores and 

 sporangia, such as I was able to show him in our 

 English and Scotch coals. He has been good 

 enough to do so ; and in a letter dated September 

 26th, 1870, he informs me that 



" Indications of spore-cases are rare, except in certain coarse 

 shaly coals and portions of coals, and in the roofs of the seams. 

 The most marked case I have yet met with is the shaly coal 

 referred to as containing Sporangites in my paper on the con- 

 ditions of accumulation of coal (" Journal of the Geological 

 Society," vol. xxii. pp. 115, 139, and 165). The purer coals cer- 

 tainly consist principally of cubical tissues with some true woody 

 matter, and the spore-cases, &c., are chiefly in the coarse and 

 shaly layers. This is my old doctrine in my two papers in the 

 " Journal of the Geological Society," and I see nothing to modify 

 it. Your observations, however, make it probable that the 

 frequent clear spots in the cannels are spore-cases." 



Dr. Dawson's results are the more remarkable, 

 as the numerous specimens of British coal, from 

 various localities, which I have examined, tell one 

 tale as to the predominance of the spore and 

 sporangium element in their composition ; and as 

 it is exactly in the finest and purest coals, such as 

 the "Better-Bed" coal of Lowmoor, that the 

 spores and sporangia obviously constitute almost 

 the entire mass of the deposit. 



Coal, such as that which has been described, is 



