INTRODUCTION. XX111 



When the eocene and other foundations of our present 

 island had risen from the deep and become the seat of 

 fresh-water lakes, receiving their tranquil deposits with 

 the abundant shells of their testaceous colonies, and 

 during the long progress of that slow and unequal eleva- 

 tion which converted chains of lakes into river-courses, 

 an extensive and varied Mammalian Fauna, as distinct 

 from the miocene as this from the eocene series, ranged the 

 banks or swam the waters of those ancient lakes and 

 rivers. Of these pliocene Mammals, we have abundant 

 evidence in the bones and teeth of successive generations 

 which have been accumulated in the undisturbed stratified 

 lacustrine and fluviatile formations. The like evidence is 

 given by the existence of similar remains in local drifts, 

 composed of gravel, exclusively derived from rocks in 

 the immediate vicinity of such drift, without a single 

 intermixture of any far transported fragments. Equally 

 conclusive and more readily appreciable proof, that the now 

 'extinct pliocene and pleistocene Mammalia actually lived 

 and died in this country, has been brought to light from 

 the dark recesses of the caves which served as lurking- 

 places for the predaceous species, and as charnel-houses to 

 their prey. 



At the period indicated by those superficial stratified 

 and unstratified deposits, the Mastodon had probably dis- 

 appeared from England : but gigantic Elephants of nearly 

 twice the bulk of the largest individuals that now exist in 

 Ceylon and Africa, roamed here in herds, if we may judge 

 from the abundance of their remains. Two-horned Ehi- 

 noceroses, of at least two species, forced their way through 

 the ancient forests, or wallowed in the swamps. The 

 lakes and rivers were tenanted by Hippopotamuses as 

 bulky and with as formidable tusks as those of Africa. 



