150 NATURAL HISTORY 



against the granite, till where it merges into the 

 iehthyolitic flagstones, and then pursued these from 

 older and lower to newer and higher layers, desi- 

 rous of ascertaining at what distance over the base 

 of the system its most ancient organisms first ap- 

 pear, and what their character and kind. And, 

 imbedded in a grayish-colored layer of hard flag, 

 somewhat less than a hundred yards over the granite 

 and about a hundred and sixty feet over the upper 

 stratum of conglomerate, I found what I sought 

 a well-marked bone, in all probability the oldest 



vertebrate remains yet discovered in Orkney 



The amateur geologists of Caithness and Orkney 

 have learned to recognize it as the ' petrified nail.' " 



To a looker-on, it would have seemed a thing of 

 little importance, that evening-stroll of the lone 

 geologist. But it was a memorable evening for 

 science and religion. The blows of that little 

 hammer are still sounding, and that "petrified nail" 

 was more fatal to the development hypothesis than 

 the tent-nail to the temple of Sisera. 



It proved that the earliest fishes were among the 

 highest organized; the order was reversed, the 



