THE ANTIQUITY OF MAN. 131 



period, — the newer pliocene ; when it was contemporary with Ele- 

 phas rneridionalis and other animals of an older fauna. It con- 

 tinued to survive until the introduction of the modern mammals, 

 and then became extinct along with Rhinoceros tichorhinus and 

 several other species, which, however, may have been of younger 

 date than itself. With these species lived the Megaceros Hiberni- 

 cus, or great Irish stag, which lasted longer, but perished before 

 the dawn of history. With them also lived the Bos prirnigenius, 

 or gigantic wild ox, the aurochs, the musk-ox, and the rein-deer. 

 The first of these existed wild until the time of Caesar ; the second 

 is still preserved in a forest in Lithuania ; the third exists now in 

 Arctic America, and the fourth still remains in Lapland. With 

 them also co-existed the wolf, the fox, the hare, the stag, and 

 other creatures still living in western Europe. 



That these creatures have been disappearing at different times 

 seems certain ; some may have been exterminated by man, but 

 the greater part must have perished from other causes. They 

 may have gone seriatim, or in considerable numbers at or near the 

 same time ; and there seems some reason to believe in a consider- 

 able and rapid decadence at the end of the post-pliocene and be- 

 ginning of the recent period. One cause which may be assigned 

 is change of climate. The climate of Europe in the time of the 

 mammoth was very cold, as indicated by the evidence of glaciers, 

 and other forms of ice action, and by the presence of the musk 

 ox. No doubt the extinction of this creature, and of the mam- 

 moth and tichorhine rhinoceros as well, would follow from the 

 amelioration in this respect as the recent period approached. This 

 change of climate depended on geographical changes, modi- 

 fying the distribution of land and water, and the direction of 

 ocean currents. A subsidence in central America or in Florida, 

 might restore the climate of the mammoth by altering the course 

 of the gulf stream ; and an elevation of land in these regions may 

 have introduced the climate of the recent period. There is abun- 

 dant evidence that much subsidence and elevation did occur while 

 these changes in organic life were in progress ; and these may, 

 more directly, by the submergence or elevation of large areas in 

 Europe itself, have tended to extinguish species, or introduce them 

 from other regions. All these points being granted, and abundant 

 evidence of them will be found given by Sir C. Lyell, it remains 

 to ask, can we convert the period required for these changes into 

 solar years? There is but one way of doing this in consistency 

 with the principles of modern geology, and this is to ascertain 



