DEVONIAN SYSTEM. 



83 



at first of pudding-stone, with which it commences, and to pass to 

 sandstone, with which it alternates at different places. Then come 



Fig. 21. Caryoplty'llia fastigia'ta. 



Fig. 23. Calceola sandalina. 



Fig. %2.Awplexus coralloi'des. 



sandstone-schists, more or less fine, different species of schist, lime- 

 stones, alternating with each other, in the midst of which are found 

 beds of anthracite. These va- 

 rious materials are differently 

 developed in different coun- 

 tries : in England the sand- 

 stones predominate. They 

 form the old red sandstone, 

 comprising strata of clay and 

 marl of different colours. In 

 other places the limestones 

 prevail with different clay- 

 slates, or chloritic schists, some- 

 times intercalated with schistose Fi - 24. C/yme'ma linea'ris. 

 quartz, as in Devonshire, and sometimes almost alone, as in Corn- 

 wall. 



37. What is the origin of the term Devonian System ? What is iti 

 geological position f Of what rocks does it consist ? 



