THE FAIRY SAILOR AND HIS COUSINS. 121 



Is not this an enemy from which the lesser tenants of the 

 deep would flee without pausing to raise the question of 

 supremacy ? These monsters maintained the ascendency 

 till the introduction of fishes, toward the close of the Upper 

 Silurian, or later. Their decline dates from this epoch ; and 

 when the voracious fishes of the Old Red Sandstone and 

 the Carboniferous Limestone came upon the stage of being, 

 the orthoceratites dwindled away. Their last representa- 

 tives barely saw the rising of Mesozoic Time. Not a trace 

 of a straight plain-chambered shell has been found in any 

 of the rocks above the Trias. They fulfilled their end in 

 creation and retired. Other carnivorous animals of a high- 

 er order were better adapted to the advancing state of the 

 earth's preparation. Garpikes appeared. A new dynasty 

 arose, to be in turn overthrown by the dynasty of the Me- 

 sozoic reptiles. 



F 



