and the Distortion of Fossils, 419 



Example 7. — Silurian Black Slate of Garth, opposite Port- 

 madoc, North Wales. 



The fossil used in this example was a tail of the Ogygia scu' 

 tator, whose normal dimensions were found to be as follows : — 



Ogygia scutator . Breadth of tail =355 

 Length of tail =203 



From these measurements, compared with the distorted fos- 

 sils, we find — 



<^ = 11°, -=2-335; 



P 



from which we obtain, by the aid of equation (6), the following 

 results : — 



a 





(G) 



This result corresponds to a greater amount of compression 

 than I found in any other case, not even excepting Tintagel, 

 where the cleavage is uncommonly well developed. 



Example '8. — Carboniferous Slates of Carrigaline, Co. Cork* 



The carboniferous slates of this district are of the same geo- 

 logical age as the slates of Ardoginna, Co» Waterford, and of the 

 same mineral character^ being dark and carbonaceous at inter- 

 vals^ with patches of smooth brown shale between the dark mud 

 bands. The fossil used to determine the amount of compression 

 is the Orthis crenistria, whose breadth equals its length in the 

 normal condition. The measurements of the distorted fossil are 

 as follow : — 



Orthis crenistria . Length =±193 

 Breadth =409 



From the specimeUj on which these measurementa were taken, 

 I obtained the following data : — 



<^=80°, i =2-119; 



r 



from which, by means of equation (6), I find — 



