344 
SILUKIA. 
[Chap. XIII. 
In concluding this Chapter, it may, indeed, be reasserted* that the 
mass of the organic remains of the Permian group constitute a remnant 
only of the earlier animals whose various developments we have followed 
in the preceding pages. They exhibit the last of the successive changes 
which these creatures underwent before their final disappearance. The 
dwindling away and extinction of many of the types which were produced 
and multiplied during the anterior epochs already announce the end of the 
long Palaeozoic period. 
In ascending above the highest of the Permian deposits, the geologist 
takes, indeed, a sudden and final leave of nearly everything in nature to 
which the words Primary, Primeval, or Palaeozoic have been or can be 
applied. 
In short, the two greatest revolutions in the extinct organic world are 
those which separated the Palaeozoic rocks from the Mesozoic or Secondary 
strata, and the latter from the Caenozoic or Tertiary and Modern deposits. 
To the consideration of these two remarkable revolutions in the history 
of former races, I shall revert in the concluding Chapter. 
* See ' Kussia-in-Europe,' vol. i. p. 205. 
