INTRODUCTION. 



IN the endeavour to complete the Natural History 

 of any class of animals, the mind seeks to penetrate the 

 mystery of its origin, and by tracing its mutations in 

 time past, to comprehend more clearly its actual condition, 

 and gain an insight into its probable destiny in time to 

 come. 



But the researches by which such knowledge is to be 

 attained are far from being complete. In many'countries 

 the fossil remains of former races of animals have been 

 neither found nor sought ; where the quest has commenced, 

 it dates but a few years back ; and in our own Island, 

 the geology and fossils of which have been as " thoroughly 

 investigated as in any other equal portion of the earth, 

 much may yet remain, even as regards the usually 

 conspicuous and easily recognizable fossils of the highly 

 organised animals which form the subject of the pre- 

 sent work, to recompense the toil of the Collector and 

 the skill of the Interpreter. Nevertheless, the evidence 

 already elicited from that part of the earth which, after 

 many changes, now constitutes the British Islands, seems 

 to afford a sufficient basis for the following outline of the 

 Ancient History of its Mammalian Fauna. 



We discern the earliest trace of warni-blooded, air- 

 breathing, viviparous quadrupeds at that remote period 

 when the deposition of the Oolitic group of limestones had 

 commenced. The massive evidence of the operations 

 of the old ocean, from which those rocks were gradually 



