368 THE CANADIAN NATURALIST. [Julie 



Trigonocarpum, and which must have belonged to phsenogams. 

 It would perhaps be unwise to insist very strongly on deductions 

 from what may be called circumstantial evidence as to the nature 

 of the fruit of Sigillaria ; but the indications pointing to the 

 conclusions above stated are so numerous that I have much con- 

 fidence that they will be vindicated by complete specimens, should 

 these be obtained. 



All of the Joggins coals, except a few shaly beds, afford 

 unequivocal evidence of Stigmaria in their underclays ; and it 

 was obviously the normal mode of growth of a coal-bed, that, a 

 more or less damp soil being provided, a forest of Sigillaria should 

 overspread this, and that the Stigmarian roots, the trunks of 

 fallen Sigillarise, their leaves and fruits, and the smaller plants 

 which grew in their shade, should accumulate in a bed of 

 vegetable matter to be subsequently converted into coal — the 

 bark of Sigillaria and allied plants affording ' bright coal,' the 

 wood and bast tissues mineral charcoal, and the herbaceous 

 matter and mould dull coal The evidence of this afforded by 

 microscopic structure I have endeavoured to illustrate in a former 

 paper.* 



The process did not commence, as some have supposed, by the 

 growth of Stigmaria in ponds or lakes. It was indeed precisely 

 the reverse of this, the Sigillaria growing in a soil more or less 

 swampy but not submerged, and the formation of coal being at 

 last arrested by submergence. I infer this from the circumstance 

 that remains of cyprids, fishes, and other aquatic animals, are 

 rarely found in the underclays and lower parts of the coal-beds, 

 but very frequently in the roofs, while it is not unusual to find 

 mineral charcoal more abundant in the lower layers of the coal. 

 For the formation of a bed of coal, the sinking and subsequent 

 burial of an area previously dry seems to have been required. 

 There are a few cases at the Joggins where Calamites and even 

 Sigillarige seem to have grown on areas liable to frequent inunda- 

 tion; but in these cases coal did not accumulate. The non- 

 laminated, slicken-sided and bleached condition of most of the 

 underclays indicates soils of considerable permanence. 



In regard to beds destitute of Stigmarian underclays, the very 

 few cases of this kind apply only to shaly coals filled with drifted 

 leaves, or to accumulations of vegetable mud capable of conversion 



* ' On the Structures in Coal,' Quart. Journ. Geol. Soc, 1859. 



