THE ANIMAL KINGDOM. 81 



sensible transitions from rocks wholly composed of entire 

 shells heaped up to strata in which they are more or less 

 finely ground down. 



Other calcareous prominences have a still more extraor- 

 dinary origin, being formed solely of microscopic beings, 

 which, although of extreme minuteness, have miraculously 

 braved the destructive action of time. I am not speaking 

 here of one of those ingenious theories which formerly 

 science was so fond of adopting. The microscope proves, 

 with a precision that cannot be contested, the truth of what 

 we advance. Ehrenberg has even given excellent figures 

 of all these marvels in his " Geological Micrography." 1 



Thus, then, when we speak metaphorically of the bones 

 of our globe, so long as the name is applied to the moun- 

 tains of coarse limestone, we are right. If it cannot be 

 looked at as the skeleton of our sphere, it can at least as 

 that of innumerable myriads which formerly peopled it. 



The geological chalk formations, which here and there 

 rise in lon^ chains of mountains, are due to similar asroflom- 

 erations of animalcules with calcareous shells, and, in spite 

 of the size of the layers, are nevertheless composed en- 

 tirely of the debris of microscopic Foraminifera. It is they 

 that encircle England with the immense rampart of beauti- 

 ful white to which it owed its ancient name of Albion. In 

 Russia, near the Volga, in the north of France, in Denmark, 



1 There can be no doubt on this point. In his Geological Micrography, Ehren- 

 berg has given plates representing numerous fossils from the chalk. They are so 

 crowded together that they touch each other. Sir Charles Lyell also, in his Geol- 

 ogy, observes that certain calcareous strata are composed of small fragments of 

 shells and coral. 



