192 AGE OF CORAL REEFS. 
time we have no evidence of any change in 
Species, but, on the contrary, the strongest proof 
of the absolute permanence of those Species 
whose past history we have been able to trace. 
Before leaving the subject of the Coral Reefs, 
I would add a few words on the succession of the 
different kinds of Polyp Corals on a Reef as com- 
pared with their structural rank and also with 
their succession in time, becaus¢ we have here 
another of those correspondences of thought, 
those intellectual links in Creation, which give 
such coherence and consistency to the whole, 
and make it intelligible to man. 
The lowest in structure among the Polyps are 
not Corals, but the single, soft-bodied Actiniz. 
They have no solid parts, and are independent 
in their mode of existence, never forming com- 
munities, like the higher members of the class. 
It might at first seem strange that independence, 
considered a sign of superiority in the higher 
animals, should here be looked upon as a mark 
of inferiority. But independence may mean 
either simple isolation, or independence of ac- 
tion; and the life of a single Polyp is no more 
independent in the sense of action than that of 
a cammmunity of Polyps. It is simply not con- 
nected with or related to the life of any others. 
The mode of development of these animals tells 
us something of the relative inferiority and su: 
