later period, are found distinct in separate families, these changes would seem to indicate in the class of Fishes, a process of Division, and of Subtraction from more perfect, rather than of Addition to less perfect forms.
Among living Fishes, many parts in the organization of the Cartilaginous tribes, (e. g. the brain, the pancreas, and organs subservient to generation,) are of a higher order than the corresponding parts in the Bony tribes; yet we find the cartilaginous family of Squaloids co-existing with bony fishes in the Transition strata, and extending with them through all geological formations, unto the present time.
In no kingdom of nature, therefore, does it seem less possible to explain the successive changes of organization, disclosed by geology, without the direct interposition of repeated acts of Creation.
CHAPTER XV.
Proofs of Designs in the Fossil Remains of Mollusks.[1]
SECTION I.
FOSSIL UNIVALVE AND BIVALVE SHELLS.
We are much limited in our means of obtaining information as to the anatomical structure of those numerous tribes of extinct animals which are comprehended under Cuvier's great division of Mollusks. Their soft and perishable bodies have almost wholly disappeared, and their external
- ↑ See note, p. 56.
