ANTARCTICA: A VANISHED AUSTRAL LAND. 315 



IJromoniis, and the raoas are their desceudants. If the forms with a 

 three-trochleaed metatarsus (from South America, Madagascar, aud 

 Kew Zeahmd) had been developed on a southern land, they could, on 

 their dispersal aud northern trek, have reached the region where they 

 now are with as much ease as by the route supposed by Mr. Wallace. 



The earliest strata in which the fossil remains of both the Northern 

 and Southern Hemisphere struthious birds have been found have been 

 determined as Eocene, but whether these were really contemporaneous 

 periods in the north and in the south, and which is the older, it is 

 impossible to tell, so that their migrations may have been quite as 

 likely from the south as from the north ; indeed, the struthious type of 

 bird is, according to Professor Parker, essentially Notogfean, The 

 African ostrich has been isolated from its congeners in the south for a 

 long period of time through the disconnection of Africa from Antarc- 

 tica, and has become specialized and lost its third metacarpal trochlea 

 and the toe it carried. Since its isolation it has spread over Africa 

 northward, but it once lived in Miocene times in Greece, in Persia, and 

 in the Siwalik region of India, Again, in New Zealand and in East 

 Australia we find a great similarity in the genera of their plants, 

 while the species they possess in common are comparatively few, which 

 is what might be expected in regions unconnected with each other 

 except through a common land at some distance — the Antarctic conti- 

 nent I have predicated, No other explanation except a common 

 southern land will satisfy the distribution of the Aphanapteryx^ the blue 

 water hens and the starlings of the Mascarene and the New Zealand 

 regions — groups of birds which are unknown on the north side of the 

 equator. 



As is well known, there live in the Galapagos Islands, on the equator, 

 off the west coast of America, giant tortoises, of which one of the most 

 remarkable facts about them is their zoological isolation. They have 

 no relations with any of the forms of their own order on the neighboring 

 continent. In several of the Mascarene Islands there lived when they 

 were first visited by Europeans enormous numbers of equally giant 

 tortoises — of which a few still survive — also in as complete isolation as 

 the Galapagos species, for they can claim no relationship with the tor- 

 toises of the nearest land, Africa. Yet, strange to say, the tortoises of 

 Aldabra and Madagascar indicate the closest affinity with those of the 

 Galapagos Islands. This extraordinary and seemingly inexjjlicable case 

 of distribution receives, in my opinion, its easiest explanation by sup- 

 posing that their ancestral home was in Antarctica, whence, forced by 

 cold aud the submergence of the land south of them, they traveled 

 north by diverging tracks, wandering, the one along the west coast of 

 America and the other toward Lemuria, where, having reached islands 

 without foes, they have prolonged their years beyond those of their 

 fellows, which have died out everywhere else. 



