150 THE GEOGRAPHY OF MAMMALS 



Southern India and South Africa. Others have maintained 

 that the points of similarity between the two faunas have 

 been exaggerated, and that no such land-connection is 

 required to account for the facts, which can easily be 

 explained on the supposition of a southward emigration of 

 northern forms due to glacial cold. 



If we go back to the early part of the secondary epoch 

 of geological time, we find, very well developed in India, a 

 geological system known as the Gondwana, composed of 

 sandstones and shales, which appear to be of fluviatile 

 origin. These beds have long afforded a problem to 

 geologists, as they cannot be at all satisfactorily correlated 

 with any formations in Europe. In South Africa, however, 

 we find a series of beds, also doubtless of fresh-water 

 origin, known as the Karroo formation, which contains a 

 nearly similar set of fossil remains, and in New South 

 Wales, again, there are formations also agreeing in the 

 characters of their fossils with the Gondwana beds. These 

 facts, according to Mr. Oldham (3), our latest authority on 

 this subject, are "inexplicable, unless there has been a 

 continuous land-communication along which plants could 

 freely migrate, and the conclusion is vastly strengthened 

 when we remember that throughout the great part, if not 

 the whole, of this period, a very different type of flora was 

 flourishing in Europe and North America." 



This land-connection may be of use in explaining the 

 distribution of some of the lower vertebrates, but is of 

 no assistance so far as the Mammals are concerned ; 

 because in those early times it is probable that none of 

 the families or even orders of our present Mammals had 

 arisen. The best-known and richest of the mammal-bearing 

 formations of India are certain beds in Sind, and the 



