128 FORMER LAND CONNECTIONS. 



Some botanists have ascribed the wide development of this 

 flora to an ability to withstand the rigorous climate, whereas the 

 northern Carboniferous plants were not so fitted. It is hence par- 

 ticularly suggestive to find that in North- Western Argentine and 

 Southern Brazil there is an actual intermingling of the two floras, 

 the northern forms probably having been derived from North 

 America. This incursion makes its appearance just after the 

 vanishing of the ice, and is also found in South Africa, but at a 

 slightly later date; in India immigration of exotic forms was slight, 

 and in Australia practically absent. 



We are fortunately in the position to decide the relative dates 

 of the invasions on the two sides of the Atlantic by the fact that 

 there is a very peculiar thin zone of carbonaceous pyritic shales 

 common to the Cape and S.W. Africa and to Brazil and Uruguay 

 in which are preserved remains of the primitive free-swimming little 

 Mesosaurus, the earliest known reptile of the southern hemisphere. 

 This is one of the many extraordinary likenesses in the strata 

 deposited at the same time in areas now a few thousand miles apart. 



There is so striking a uniformity in the indigenous floral 

 assemblages of the several regions referred to as to compel us to the 

 recognition of the latter as parts of one ancient continent; this 

 applies not only to one particular geological stage, but to the whole 

 time-interval during which Gondwanaland existed, namely, from 

 the Upper Carboniferous to the Jurassic. There is a community 

 of genera and of species testifying to a lack of hindrances to floral 

 migration in the south precisely as was the case in the north with 

 the northern flora throughout the identical period. 



At one time, in the late Permian, Glossopteris itself spread 

 outside the recognised borders of Gondwanaland and actually 

 reached Northern Russia, though failing to establish a secure foot- 

 hold. The subsequent developments of the southern flora show on 

 the contrary that an invasion by northern forms took place, con- 

 nection with Europe becoming freer, and Glossopteris, although 

 lingering on into the Upper Triassic in Natal and Indo-China, was 

 extinguished by the incoming of hordes of cycads, conifers, and 

 ferns. In this manner the plant life of the southern hemisphere 

 came to approximate very closely to that of the northern, and 

 the uniformity thus established in Rhaetic (late Triassic) times 

 persisted all over the globe until late in the Jurassic. 



Permian and Triassic Vertebrate Life. 



The record of the vertebrate life is both ample and corrobora- 

 tive. Probably few persons are aware of the numerous and mar- 

 vellous finds that have been made in the Karroo Beds since the 

 days of Bain and Atherstone, discoveries that are not only helping 

 to fill up the many gaps in the palaeontological record, but are 

 throwing much light upon the conditions that prevailed. 



The Pareiasaurians, for example, were heavily built reptiles 

 with a length of 8 or 9 feet, possessing broad flattened skulls, jaws 

 bordered by uniform, serrated teeth, powerful limbs and claws 

 which indicate digging abilities. Their skeletons have generally 



