SOME EARLY MAMMALS 259 



matrix that the brain-cavity and the openings leading from it 

 could be worked out without difficulty. 



It is about forty-one years since the wonderful forms of life 

 sealed up within these Eocene lake-deposits first became known 

 to science. Long before then, however, the wandering Indian 

 had been accustomed to seeing strange-looking skulls and 

 skeletons that peeped out upon him from the sides of canons and 

 hills, as the rocks that enclosed them crumbled away under the 

 influence of atmospheric agents of change the ceaseless working 

 of wind, rain, heat, and cold. To his untrained mind no other 

 explanation suggested itself than the idea that these were the 

 bones of his ancestors, which it would be highly impious to 

 disturb. Eequiescant in pace! So he left them in peace. 

 Perhaps he believed in a former race of human giants ; if so, 

 these would be their bones. Long before Professor Marsh's 

 expeditions, the earliest squatters, trappers, and others used to 

 bring back news of marvellous monsters grinning from the ledges 

 of rock beneath which they camped. At last these tales attracted 

 the notice of some enthusiastic naturalists in the eastern States. 

 Professor Leidy obtained a number of bones, from which he was 

 able to bring to light an extinct creature at that time unknown 

 to science, namely, the Uintatherium. Professor Cope also 

 described some extinct animals disinterred by himself from the 

 same region. 



But our knowledge of the Dinocerata is chiefly due to Professor 

 Marsh, who has despatched one expedition after another, and 

 who, after many years of laborious research both in the western 

 deserts and in his wonderful collection at Yale College, has 

 published a splendid monograph on the subject. No trouble 

 and no expense have been spared in order to obtain material for 

 this great work, and all geologists must feel grateful to Professor 



