298 THE OLDEST AIR-BREATHERS 



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. Alternations 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, 1 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 unusual to 

 find every little runnel or pool full of marine shell fish, while in 

 the higher parts of the marsh land plants are growing ; and 

 in. such places the deposit formed must contain a mixture of 

 land plants and marine animals with salt grasses and herbage 

 the whole in situ? 



These considerations serve, I think, to explain all the 

 apparently anomalous associations of coal plants with marine 

 fossils ; and I do not know any other arguments of apparent 

 weight that can be adduced in favour of the marine or even 



1 Journal of Geological Society, vol. xi. 



2 In the marshes at the mouth of Scarborough River, in Maine, channels 

 not more than a foot wide, and far from the sea, are full of Mussels and 

 Myae; and in little pools communicating with these channels there are 

 often many young Limuli, which seem to prefer such places, and the cast- 

 off shells and other remains of which may become imbedded in mud and 

 mixed with land plants, just as in the shales of the coal measures. 



