CHARLES B. WARRING. 59 
of plants and animals. There is indisputable evidence 
that the present is only the last of a long series of ‘*‘ pop- 
ulations,’ each differing from its immediate predecessor. 
Each antecedent population was of a lower grade than 
its successor, until at last we reach the dawn of life where 
only the lowest orders are found. Or, conversely, start- 
ing at the beginning of life, there were for millions of 
years radiates, articulates, and mollusks, but no verte- 
brates ; then for other millions, there were water verte- 
brates, but none on the land ; then for thousands of cen- 
turies, land vertebrates but no mammals, and for another 
long period, mammals, but none of existing kinds, and 
lastly those now living. 
One example will suffice, although it reaches back but 
a little way, yet far enough for my present purpose. 
Many thousand years ago, there lived an animal which 
geologists have named Orohippus, or the Mountain 
Horse. It was about the size of a very small Shetland 
pony, which in many respects it resembled. Still it was 
not a horse, for it had four little hoofs on each fore foot, 
and three on each of its hind ones. The genus lived 
many thousand years, each generation like its predeces- 
sor; but at last ‘‘from some cause unknown to science,”’ 
a new animal, in fact a new genus, appeared, different in 
some respects from the Orohippus, and approximating 
somewhat more to the present horse, yet not a horse, for 
on each of its feet were three hoofs. The Mesohippus, 
for so geologists have named it, also kept on for many 
generations, producing at every birth only its own like- 
ness. After a uniform course, for we know not how 
many thousands of years, there appeared another crea 
ture, the Miohippus, very much like its predecessor, but 
- approaching more nearly to the horse. The middle hoof 
was larger, indicating a promise of an animal in which 
the two side hoofs should disappear. The Miohippus 
lived from generation to generation its uneventful life, 
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