GEOLOG Y. 123 
progress of the higher forms of life from the lower. The 
Brachiopods, the lowest of Mollusca, the Crinoids and 
Star-fish, the lowest of Echinodermata, and the Trilobites, 
among the lowest of Crustacea, abounded in the Paleozoic 
Age. The Crinoids and Brachiopods lived on through 
Secondary time, playing, however, an inferior röle, and 
now have almost passed away, a few Brachiopods only and 
one Crinoid living at the present day. The Age of Mol- 
lusca, we have seen, was folowed by an Age of Fishes, 
thus exhibiting a progress in the animal life of the globe. 
The fact of these fishes being Sharks and Ganoids is very 
significant: the important point to be noticed is, that what- 
ever view be taken of the rank of the Ganoids among fish, 
they preceded the Teliosts and Batrachia, and that 
the Sharks with pavement teeth came before those with 
cutting teeth. The next two periods offer a further pro- 
gress in the life of the globe, since we find the Batrachia 
(Frogs, Labyrinthodons) appearing in the Carboniferous, 
folloved by the Reptiles (Proterosaurus) in the Permian, 
while the Insects are represented by the lower orders, of 
which the Neuroptera (May-flies) were very abundant in 
the Carboniferous. In the Secondary Age the Reptiles 
reach their climax, while the Bony Fishes, Mammals, and 
Birds are just appearing. The gradual unfolding of the 
vegetal kingdom during the Primary and Secondary Ages 
is as marked as that of the animal kingdom. An Age of 
Algz was followed by an Age of Acrogens; these gave 
way to Cycade and Conifere; the Cycadz, in their turn 
dying out, were replaced by the Palms of the Tertiary, 
associated with which are the Forest trees, among which 
the great Mammals lived, and the flowering plants offered 
then as now a resting-place for butterflies, which first 
appeared in this age. 
Modern Geologists do not believe that life, since it first 
appeared, has ever been extinct all over the globe at the 
