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ON THE ZOOLOGICAL EVIDENCE KELATING TO 

 ANCIENT LAND CONNECTIONS BETWEEN AFKICA AND 

 OTHEK PORTIONS OF THE SOUTHERN HEMISPHERE, 



BY 



John Hewitt, B.A., 

 Dirccior of fJic Albaini Muscitm, G raliamsioien. 



Read July 13, 1922. 



In a recent number of this Journal (Vol. XVIII (1921), p 

 120) there appeared an important paper by Dr. A. L. du Toit 

 on " Land connections between the other continents and South 

 Africa in the past." Many writers have risked their reputations 

 on this elusive subject. In modified form its literature takes us back 

 to the dawn of human history, for, according to some students, 

 the great island of Atlantis, recorded by Herodotus as Egyptian 

 tradition, was actually a remnant of some old trans-atlantic land 

 bridge. In modern times, zoologists and botanists alike have 

 thought it necessary to invoke certain land connections between 

 the continents in order to explain the facts of present-day distri- 

 bution of animals and plants. It is true that the evidence 

 submitted has been somewhat lacking on the geological side, yet 

 the distributionists have clearly imderstood that such hypotheses 

 are only permissible when no simpler explanation seems possible, 

 and that an acceptable theory must have some geological data 

 in its framework. Certain ancient land connections, such as that 

 between Alaska and Northern Asia during the greater portion of 

 the Tertiary period, are conceded by the most conservative 

 authorities, but there is less agreement on the question of former 

 connections between Africa and South America, or between Africa 

 and Australia. A definite pronouncement on this problem, from 

 the aspect of a leading geologist, is therefore of particular value 

 to those of us who are interested in the study of zoogeography. 



Dr. du Toit's views, based on those of Wegener, may be 

 summarised as follows : A great southern continent, Gondwana- 

 land, linked together South America, Africa, Madagascar, India, 

 Australia, and even Antarctica, almost throughout the Upper 

 Carboniferous, Permian, Triassic and Jurassic times. This 

 hypothetical continent was not the vast area i-epresented by 

 Prof. Suess and many other writers. Instead, Dr. du Toit 

 pictures the ancient land mass in inuch attenuated form, and 

 the present continents as derived therefrom by forcible disruption 

 of parts which gradually became widely separated. The other 

 view involves no migration of continents, for the submergence 

 of a vast land area in what is now the South Atlantic ocean is 

 presumed to bring about the present continental conditions. 



During Jurassic times, the connection between Australia and 

 Africa seems to liave been interrupted by a marine invasion. 



