114 Geological Socrety of London. 
ments give information regarding the condition of the ancient sea 
and ancient atmosphere, and the relations of both these media to 
light. The fluid in which these marine animals lived at remote pe- 
riods must have been pure and transparent to allow the passage of 
light to organs of vision resembling those of living Crustaceans ; and 
this train of reasoning naturally leads us still further, and to more 
important consequences, when we reflect on the general adoption of 
the undulatory theory of light, and the connexion between light, 
heat, electricity, and magnetism. 
I have heard it objected, that the zoologist and botanist had al- 
ready advanced such abundant proofs of design in the construction 
of living animals, and plants, that the auxiliary evidence of paleon- 
tology was useless, and that to appeal to fossils in support of the same 
views was to add weaker to stronger arguments. In the living ani- 
mal, it is said, we can study its entire organization, observe its habits, 
see the manner in which it applies each organ, and so verify with 
certainty the ends for which any particular member was formed and 
fashioned. But in the case of the fossil, we have first to infer the 
greater part of the organization from such parts as alone remain, 
and then further to infer from analogy the habits and functions dis- 
charged, and lastly the former conditions of existence of the crea- 
tures so restored. If then we occasionally fall into error when spec- 
ulating on the use of the organs of living species, how much more 
easily may we be deceived in regard to the fossil ! 
In answering this objection, it cannot be denied that the data sup- 
plied by paleontology are less complete; but they are nevertheless 
abundantly sufficient to establish a very close analogy between ex- 
tinct and recent species, so as to leave no doubt on the mind that the 
same harmony of parts and beauty of contrivance which we admire 
in the living creature has equally characterized the organic world at 
remote periods. If this be granted, it is enough; the geologist can 
then bring new and original arguments from fossil remains to bear 
on that part of natural theology which seeks to extend and exalt 
our conceptions of the intelligence, power, wisdom, and unity of 
design manifested in the creation. 
It can now be shown that the configuration of the earth’s surface 
has been remodelled again and again; mountain chains have been 
raised or sunk,\ valleys have been formed, again filled up, and then 
re-excavated, sea and land have changed places, yet throughout all 
these revolutions, and the consequent alterations of local and gene- 
