114 



PISHES OF THE SILURIAN ROCKS, 



show how iclithyic discovery has in its slow course penetrated 

 into the depths, I shall retain the divisions recognised as those 

 of the system when that course began. The highest or most 



5Z5 S 



i 



Upper Ludlow. 

 Aymestry Limestone. 

 Lower Ludlow. 



Wenlock Limestone. 

 Wenlock Shale. 



Caradoc Sandstone, &c. 

 Llandeilo Flags, &;c. 



Plynlimmon Group. 

 Bala Limestone. 



Snowdon Group 



Fish, 1838, (Murchison). 

 Fish, 1842, (PhiUips). 



Fish, 1845, (Sedgwick). 

 Fish, 1846, (Sillunan). 



Fish, 1847, (Phillips). 



Fish, 1847, (Sedgwick). 



Fish, 1847, (Geologists 

 of Government Sur- 

 vey). 



Fucoids. 



