266 Evolution and Distribution of Fishes 



or river life. This is eminently true of the Scottish, the 

 Canadian, and the Russian strata, as already described 

 (P- ^3S)- The writer has collected specimens in the Calci- 

 ferous rocks of Water-of-Leith that lay beside fern and 

 lepldodendroid remains, but no suggested trace of marine 

 organisms was found. The coal-Measure rocks of Carluke, 

 of Midlothian, of Yorkshire, and of Staffordshire in 

 Britain, all contain the genus alongside plants, Estheria, 

 occasional scorpions, and eurypterids. 



But according to much of past accepted opinion, 

 the conditions and relations for Acanthodes seemed to be 

 very different for eastern and central North American 

 strata. For the view has been almost universally expressed 

 that the greater part of the Old Red or Devonian, con- 

 sisted of rocks of marine origin. The writer has already 

 touched slightly on this problem (p. 126), but he desires 

 now to discuss it in fuller detail, and not least owing to 

 its important bearing on the origin and distribution of the 

 Arthrodira, that are treated of later (p. 294). 



In the elaborate memoirs of the New York, Pennsyl- 

 vania, Ohio, Illinois, Iowa, and other surveys, it is either 

 tacitly or openly accepted that the Devonian strata and 

 their fossils are of marine origin. We need scarcely linger 

 now over reasons for this, as some are explained below. 

 Instead also of dealing with all of the above memoirs, the 

 writer proposes to confine attention mainly to those of the 

 Ohio survey, supplementing with results recently secured 

 by Eastman and others. 



Newberry, in his excellent volumes of the Ohio survey, 

 and in his monograph on the palaeozoic fishes of North 

 America {86) has dealt with the subject most fully. 

 As he sets forth by diagram in Vol. i, pt. i of the Ohio vol- 

 umes he divided the Devonian of Ohio into the Oriskany, 

 the Corniferous, the Hamilton, the Huron and the Erie 

 zones. The second of these he subdivided into a lower or 

 Columbus limestone, and an upper Delaware or Sandusky 

 limestone, since the two differed markedly in character and 

 fossils Superior to the Devonian he placed, as Lower Car- 

 boniferous rocks, the groups named Cleveland Shale, and 

 Waverley beds, the latter being subdivided into Bedford 



