many million years ago. They clustered in the twilight and captured their prey ages before man came on this earth. Some time, doubtless, the earlier rocks will reveal the remains of their immediate ancestry, which is not now known.
In all these chapters I take it for granted that all our forms of life are outgrowths from older and different forms. There are about ten million different species of animal and vegetable life now known to science, and there are vast numbers of microbes that are visible only with the best microscopes. All observation and reasoning warrant the belief that there were not ten million separate creations, but they are the varied branches from one or a few original living creatures of simple structure. We can say with certainty that all naturalists take that view of the matter, because it explains numerous difficulties, and harmonizes conflicting phenomena.