This very slight glance at the most prominent indications of the primeval state of the country, will suffice to convey some idea of the circumstances under which the aboriginal colonists entered on the possession of the British Isles. Other portions of the same line of argument, derived from the fossil mammalia, and the circumstances under which they are discovered, will come under review in the course of our inquiries. The fossil Cetacea, especially, furnish most interesting and conclusive evidence of the very remote period at which the presence of a human population is discoverable in Scotland, while the beaver, (_Castor Europæus_,) which is frequently found in a fossil state, is also proved to have existed as a living species, both in Scotland and Wales, down to the twelfth century, and is even referred to so late as the fifteenth century. To the abundance of wild animals which continued to occupy the moors and forests of Scotland, long after the primitive states of society had entirely passed away, we shall also have occasion hereafter to refer. The same causes which exterminated the huge urus, the cave bear, and others of the largest and most intractable of the wild denizens of the British forests, ultimately led to the extinction of the greater number of those which either supplied objects of the chase, or were inimical to the social progress of man. Thus we observe, in the economy of nature, that one species after another disappears, to make way for newer occupants, until at length the last of those huge preadamite races of being give place, before the gradual advancement of man to assume possession of terrestrial dominion. Yet on this point also those questions in historic chronology, which tend to determine more precisely the lapse of centuries intervening between the Adamic creation and the earliest era of authentic history, exercise an important influence. Geology leaves no room for questioning the fact, that man did not enter upon this earth after some tremendous cosmical revolution, which made way for an entirely new race of beings, but that he was introduced as the lord of an inheritance already in possession of many inferior orders of creation. Contemporary with the most remarkable cave fossils are found the remains of many historic, or still existing species, and the precise line has yet to be drawn which shall determine how many of these were extinct, at the period when the Creator, at length satisfied with his inferior works, said, "Let us make man in our image, after our likeness." The remains, both of the large cave hyæna, (_Hyæna spelæa_,) and of the great cave tiger, (_Felis spelæa_,) occur not only in ossiferous caverns, but have also been found in superficial unstratified deposits. Considerable portions of the skeleton of the latter were discovered in 1829, along with remains of the mammoth, rhinoceros, ox, stag, and horse, in a marl-pit near North Cliff, Yorkshire.