In Carboniferous and Permian Epochs 141 



poor in fish remains, is passed, we come to a new fauna, 

 from which nearly all of the Lower Carboniferous species 

 and with them also a number of genera have disappeared, 

 their place being taken by an Upper Carboniferous assem- 

 blage, which in its main features is characteristic not only of 

 the Coal Measures of Scotland, but of the Lower and 

 Middle Coal measures of England, extending also into the 

 transition series of the latter country." 



Long-continued and increasing environal changes in the 

 wide continental areas inhabited by the two groups of fishes 

 he here compared, could only result in a changed facies of 

 the species he refers to. In this connection Rupert-Jones 

 very neatly remarks : "All animals may have been marine, 

 subsequently brakish or freshwater, and this may have 

 been the case with Estheria^ but except for the progressive 

 aspect of the argument, the converse might just as well hold 

 good for the Lingiila^ the Spirorbis, Avicida, Anthracosia, 

 Anthracomya, and Pleurophorus, mentioned as being found 

 in the older rocks in company with Estheria." 



What actually happened for fishes is fully set forth in 

 a succeeding chapter. Here it may shortly be said that 

 while the ganoids, crossopterygians, and not a few elasmo- 

 branchs remained in their former freshwater habitats, a 

 gradual migration of some lithe, predaceous and powerful 

 elasmobranchs into the sea took place during late Upper 

 Old Red or more likely during Lower Carboniferous time. 

 Then, and then only, their remains begin to appear along- 

 side typical invertebrate marine forms, and this condition 

 persists into the Upper Carboniferous or even Lower 

 Permian. 



As to the nature and successional relation of the chief 

 fossiliferous beds of the Calciferous series round Edin- 

 burgh, the accompanying table (Fig. 17) from one of 

 Traquair's extensive papers (77: plate i) will illustrate, 

 while it also sets forth the thickness of the beds. From a 

 fairly intimate acquaintance with them the writer would re- 

 gard the Craigleith sandstones and Wardie shales, the 

 Burdiehouse limestone, the uppermost "Oil shales" and all 

 of the connecting beds between these as purely freshwater, 



