558 GEOLOGY 



runners of the abundant fishes of the Old Red Sandstone of the 

 Devonian. As the sand of this formation was probably deposited 

 by land waters, the association of the fish with eurypterids and land 

 plants carries some further presumption that the peculiar crustacean 

 fauna lived normally in land waters. It is not to be overlooked, 

 however, that in the transition beds the fishes are also associated 

 with marine fossils, and there is no question that, before the close 

 of the Devonian period, certain fishes at least were truly marine. 

 Map work. See note at end of Chapter XVII, page 535. 



