xxvi INTEODUCnON. 



a number of authors, including, among others, Ameghino *, Blanford f , Boulenger $, 

 Lydekker^, NeumayrH, Ortmann^, Scott**, Suessff, and von Ihering J:}:. These 

 writers, basing their arguments on many diverse kinds of evidence, all seem 

 to arrive at the general conclusion that a land-connection did exist betvpeen 

 Africa and South America throughout at least most of the Secondary period. and 

 may have persisted into the Lower Tertiary. Concerning the precise position 

 of this land-connection, and whether it may have existed at more than one point, 

 there is some diversity of opinion, but these differences do not seem to be of 

 any great importance compared with the general agreement that there must have 

 been such a connection. Speaking generally, it appears that (1) probably in 

 Jurassic times Africa and South America formed a continuous land-mass ; (2) in 

 the Cretaceous period the sea encroached southwards over this land, forming 

 what is now the South Atlantic. How far this depression had advanced southwards 

 at the end of the Secondary period is not clear, but it appears certain that the 

 final separation of the two continents did not take place till Eocene times, and 

 that there may have been a chain of islands between the northern part of Africa 

 and Brazil which persisted even till the Miocene §§. 



On the assumption that this series of events did happen, there is little difficulty in 

 accounting for most of the peculiarities in the distribution of the various groups. 

 Thus, to mention only a few instances, the presence in both continents of the Hystrico- 

 morphine Eodents, of Chelonians of the family Pelomedusidse, and of the Fishes of the 

 family Cichlidse is at once accounted for. So also is the presence in the Santa Cruz 



* La Argentina al traves de las Ultimas Epocas Geologicas (Bueuos Aires, 1897). Also "Linea 

 Rlogenetica de los Proboscideos," Anales Mus. Nac. Buenos Aires, vol. viii. (1902) p. 19 ; and " Les 

 Edentes fossiles de Prance et dAllemagne," loc. eit. vol. xiii. (1905) p. 175. 



t Presidential Address to the Geological Society, 1890. 



J Presidential Address to the Zoological Section, Brit. Assoc. (South Africa, 1905). 



§ A Geographical History of Mammals (1896), p. 127. 



li Erdgeschichte (1890), p. 376. 



% " Geographical Distribution of Freshwater Decapods and its Bearing on Ancient Geography," Proc. 

 Amer. Phil. Soc. vol. xli. (1902) p. 267. 



** Eeports of the Princeton University Expeditions to Patagonia (1896-1899) — Palaeontology, vol. v. 

 pt. ii. (1905). 



tt Das Antlitz der Erde, vol. ii. (1888). 



Jt " On the Ancient Eelations between New Zealand and South America," Trans. New Zealand Instit. 

 vol. XXV. (1891) p. 431. 



§§ Eor evidence of the probable existence of shallow water across this region, perhaps as late as the 

 Miocene, see Gregory, Quart. Journ. Geol. Soc. vol. li. (1895) p. 306. 



