210 THE HISTORY OF CREATION. 
teeth and fin-spikes. These are found in the older 
formations in such quantities, varieties, and sizes, that we 
may, with certainty, infer a very considerable develop- 
ment of Primzeval fish in those remote ages. They are even 
found in the Silurian strata, which contain but few 
remains of other Vertebrata, such as Enamelled fish (and 
these only in the most recent part, that is, in the upper 
Silurian). By far the most important and interesting of 
the three orders of Primeval fish are Sharks; of all still 
living double-nostriled animals, they are probably most 
closely allied to the original primary form of the whole 
group, namely, to the Proselachii. Out of these Proselachii, 
which probably differed but little from genuine Sharks, 
Enamelled fish, and the present Primzeval fish, in all prob- 
ability, developed in one direction, and the Dipneusta, 
Sea-dragons, and Amphibia in another. 
The Ganoid, or Enamelled fish (Ganoides), in regard to 
their anatomy stand midway between the Primeval and the 
Osseous fish. In many characteristics they agree with the 
former, and in many others with the latter. Hence, we infer 
that genealogically they form the transition from Primeval 
to Osseous fish. The Ganoids are for the most part extinct, 
and more nearly so than the Primeval fish, whereas they 
were developed in great force during the entire palzeolithic 
and mesolithic periods. Ganoid fish are divided into 
three legions according to the form of their external 
covering, namely, Mailed, Angular-scaled, and Round- 
scaled. The Mailed Ganoid fish (Tabuliferi) are the oldest, 
and are directly allied to the Selachii, out of which they 
originated. Fossil remains of them, though rare, are found 
even in the upper Silurian (Pteraspis ludensis of the 
