ON THE ORIGIN OF COAL. 157 



vegetable matter, which grew on dry land, on the 

 spots where it is now found ; or those who merely 

 contend that such vegetable matter grew on the 

 spots where it is now found, without stating 

 whether it grew on dry land or in water must 

 admit of the existence of a subsiding area in 

 their different views. 



Different opinions have been held, as to whether 

 the waters which formerly prevailed, during the 

 deposition of the higher part of the carboniferous 

 series were fresh or salt. The authors who take 

 the former view, adduce in support of their 

 hypothesis the remains of a Cypris, and a ques. 

 tionable species or two of Unio ; whilst those of 

 the latter adduce shells of the genera, Goniatites, 

 Nautilus, Posidonia, Pecten, Modiola, and Nucula, 

 the great Sauroid and Squaloid fishes, as well as 

 those of the Platysomus, Cselacanthus, Palaeoniscus, 

 &c. genera common to the carboniferous, and the 

 magnesian limestone formations. Whether the 

 strata contain the remains of fishes, Pecten, 

 Goniatites or Unio, the remains of such plants 

 as the Sigillaria and its Stigmaria roots are 

 equally present ; which would not be expected to 

 be the case if sudden changes of the waters, 

 from fresh to salt, had taken place ; for a Flora is 



