GENERAL INFERENCES. 73 



CHAPTER V. 



GENERAL INFERENCES. 



1. The joosi^io?z of the Yellow Sandstone. This we consider 

 to be clearly estabhshed both by its mineral relations and fossil 

 remains. Step by step the Devonian series is well defined, in 

 the order of superposition, from the Grampians into the opening 

 of Dura Den, where the Clashbennie red deposit immediately 

 underlies the yellow beds of the locality. There is no other 

 line of demarcation than what occurs among the divisions of 

 the series ; and it may be safely averred that, in no quarter of 

 the world yet examined is there a group of rocks similar to 

 those of Dura Den, unequivocally attested or asserted to belong 

 to the coal measures. But the fossil remains, in all their 

 types and characters, are clearly sufficient in themselves to 

 determine the question. The pterichthyan forms are only 

 found in the middle series of the Old Red, while the numerical 

 abundance of the holoptychian tribe, in conjunction with so 

 many allied fishes, all of the ganoid granulated scale order, 

 establish relations up and down through the whole Devonian 

 system that must satisfy the most scrupulous inquirer on the 

 point at issue. Dura Den yellow sandstone, in its geognostic 

 position, mineral qualities, and fossil organisms, vindicates the 

 claim to be ranked among the rocks of the great Fish Epoch 

 rather than to be alKed with those which enclose the flora of 

 the succeeding age of gigantic vegetables and mountain chains 

 of shelly limestone, — not a shell or vestige of plant being any- 



