154 FIELD GEOLOGY. 



Orthis rustica, we should be sure that the rock be- 

 longed to the Wenlock group, and was the second of 

 the three limestones above mentioned. 



As the application of fossil evidence has often a very 

 practical bearing, we may take even another instance 

 from the history of coal-mining : it has frequently hap- 

 pened that much labour and money have been fruitlessly 

 wasted in the search for coal, which would have been 

 prevented by the slightest acquaintance with the laws 

 of palaeontology, the beds through which shafts have 

 been sunk yielding fossils, not of the species mentioned 

 on p. 142, but such as are characteristic of Silurian 

 shales or Kimmeridge clay. 



The late Mr. J. B. Jukes says : " I have known, even 

 in the rich coal district of South Staffordshire, shafts 

 continued down below the Coal-measures, deep into the 

 Silurian shales, with crowds of fossils brought up in 

 every bucket, and the sinker still expecting to find coal 

 in beds below those Silurian fossils. I have known 

 deep and expensive shafts sunk in beds too far above 

 the coal-measures for their ever being reached, and 

 similar expensive shafts sunk in black shales and slates 

 in the lower rocks far below the coal-measures, where a 

 pit might be sunk to the centre of the earth without 

 ever meeting with coal. Nor are these fruitless enter- 

 prises a thing of the past. They are still going on in 

 spite of the silent warnings of the fossils in the rocks 

 around, and in spite of the loudly-expressed warnings 

 of the geologists, who understand them, but who are 

 supposed still to be vain theorists, and not to know so- 

 much as the ' practical man.' Within my own expe- 

 rience large sums of money have been absolutely thrown 



