286 AIR-BREATHERS OF THE COAL PERIOD. 



ter in large quantity is proved by the occurrence of the mineral 

 charcoal of the coal itself, as I have elsewhere shown.* The erect 

 trees which occur at so many levels, also imply sub-aerial decay. A 

 tree imbedded in sediment and remaining under water, could not 

 decay so as to become hollow and deposit the remains of its wood 

 in the state of mineral charcoal within the hollow bark. Yet 

 this is the case with the greater part of the erect sigillariae which 

 occur at more than 20 levels in the Joggins section. Nor could 

 such hollow trunks become repositories for millipedes, snails and 

 reptiles, if under water. On the other hand, if, as seems neces- 

 sary to explain the character of the reptiliferous erect trees, these 

 remained dry or nearly so in the interior, this would imply not 

 merely a soil out of water, but comparatively well drained ; as 

 would indeed always be the case, when a flat resting on a sandy 

 subsoil was raised several feet above the level of the water. 

 Farther, though the peculiar character of the roots of Sigillarice 

 and Catamites may lend some countenance to the supposition that 

 they could grow under water or in water-soaked soils, this 

 will not apply to coniferous trees, to ferns, and other plants, 

 which are found under circumstances which show that they grew 

 with the Sigillarice. 



In the coal measures of Nova Scotia, therefore, while marine 

 conditions are absent, there are ample evidences of fresh-water or 

 brackish-water conditions, and of land surfaces, suitable for the 

 air-breathing animals of the period. Nor do I believe that the 

 coal measures of Nova Scotia were exceptional in this respect. It 

 is true that in Great Britain evidences of marine life do occur in 

 the coal measures ; but not, so far as I am aware, in circumstances 

 which justify the inference that the coal is of marine origin. Al- 

 ternations of marine and land remains, and even mixtures of 

 these, are frequent in modern submarine forests. When we find 

 as at Fort Lawrence in Nova Scotia, a modern forest rooted in 

 upland soil forty feet below high-water mark, f and covered with 

 mud containing living Tellinas and Myas, we are not justified in 

 inferring that this forest grew in the sea. We rather infer that 

 subsidence has occurred. In modern salt marshes it is not un- 

 usual to find every little runnel or pool full of marine shellfish, 

 while in the higher parts of the marsh land plants are growing . 



* Journal of Geological Survey, vol. XV. 

 f Journal of Geological Society, vol. XI 



