EVIDENCE FROM PALAEONTOLOGY 113 



but is smaller than in later forms, and is followed by 

 two other incisors and a canine. The lower jaw also 

 has three incisors on each side, but has lost the 

 canine. The skull is without horns and the skeleton 

 is much lighter and more tapir-like in its proportions 

 and the whole animal decidedly smaller than the 

 existing rhinoceroses; the front foot has four toes, but 

 the external one (the fifth of the original five), is 

 already much reduced in size and evidently dwindling 

 away. From the Oligocene to the Pliocene, inclusive, 

 North America had an abundance of rhinoceroses, 

 both horned and hornless, but finally they disap- 

 peared from the continent entirely. 



In the uppermost part of the lower Oligocene occur 

 rhinoceroses which have the beginnings of a trans- 

 verse pair of horns on the nose; in the upper Oligo- 

 cene these have increased to full size and this gives 

 us the exceptional series of paired-horn rhinoceroses 

 referred to above. In the lower Miocene the series 

 was represented by its terminal member, a very small 

 animal, of which immense herds lived on the Great 

 Plains. Near Agate, Nebraska, is a bed, perhaps an 

 ancient quicksand, which contains the bones of this 

 little rhinoceros in incredible quantities. 



The story of the rhinoceroses, their development 

 and their wanderings, is a fascinating one, but, un- 

 fortunately, only this bald sketch can be given, from 

 which the most interesting details have been omitted. 

 Their testimony, so far as it goes, is just the same as 

 in the other genealogical series, gradual differentia- 



