ANTARCTICA. 285 



the other Hemisphere by either of them, and the fact that both 

 have a circumpolar distribution, must signify a close association 

 of the land areas of the Northern Hemisphere, and a correspond- 

 ing intimate relation between the continents of the Southern 

 Hemisphere. Otherwise it is hard to understand why two such 

 groups should have such a complete circumpolar distribution in 

 tluir respective hemispheres. 



The Phreodrilidae have been preserved for us on the tops of 

 the mountains, ami apparently in abundance in South Africa, as 

 living relics of the fauna which flourished in that old land area — 

 Gondwanaland — which once linked up our Southern continents, 

 stretching across the x\tlantic and Indian Oceans. If we can 

 regard their adaptation to low temperatures as a common ances- 

 tral character, they may be forms whose distribution was greatly 

 helped in a circumpolar direction by the glacial conditions which 

 obtained during the time of existence of Gondwanaland. 



Many other examples with a similar limited distribution 

 could he mentioned, but in many of them we cannot put too much 

 reliance. At all events, although many of them may not offer 

 such clear proof of southern land connections as the examples 

 chosen, yet their distribution is readily explained by the assump- 

 tion of that connection, and when taken into consideration in 

 conjunction with the special examples chosen, may be regarded 

 as corroborating the conclusions drawn from those examples. 



For example : the blind snakes — Typhlopidse — are restricted 

 to Australia, India, Africa, Central and South America ; Cystig- 

 nathid frogs are restricted to Australia, Tasmania, South 

 America, Central America, and the southern portion of North 

 America. These limited distributions receive support from the 

 negative evidences of Palaeontology. We then see that there is 

 strong evidence in support of a closer relation between the 

 Southern continents inter sc, and Antarctica. 



The next question concerns the time during which such con- 

 nections existed. In this inquiry we are assisted by the fossil 

 reptiles which are well represented in the Karroo rocks of South 

 Africa. The earliest fossil reptile known in South Africa is a 

 form — Mesosaurus — which was found in the lowest Karroo beds, 

 namely, the Dwyka strata. Strangely enough this form preceded 

 the bulk of the Karroo reptiles by a long period, and is very 

 similar to an American form. That both the South American 

 and African forms had a common ancestor there can be no doubt, 

 and the occurrence of practically the same form in both these 

 land areas is well explained by the existence of a trans-Atlantic 

 land bridge, at the end of Palaeozoic times — Permo-Car- 

 boniferous. The original home of the South African reptiles, 

 judging from their relative times of appearance in America and 

 South Africa, seems to have been in the northern portion of 

 South America. 



The long interval between the arrival of Mesosaurus and the 

 succeeding forms in South Africa is to be explained by the 



