130 THE NEOG^EIC REALM. [CHAP. 



country, they could not have reached their present habitat till the 

 end of the Miocene. 



On the question of the southern or northern origin of some of 

 the above-mentioned birds, Professor Huxley 1 , so far back as 1868, 

 wrote as follows: "I watch the progress of M. Alphonse Milne- 

 Edwards's researches with great interest, to know whether parrots, 

 pigeons, Dromceidce (Casuariidas) and Rhtzidce occur in force, or 

 at all, among the Miocene birds. If they are absent from the 

 Miocene fauna of Arctogaea, it will be necessary to suppose that 

 these groups of birds are of sufficiently ancient origin to have been 

 separated, even before the Miocene epoch in Austro-Columbia 

 (Neogaea) and Australasia, whence they have subsequently 

 colonised part of Arctogsea ; while, on the other hand, their 

 presence in European Miocene formations will render it possible 

 that the colonisation has taken place the other way, and that these 

 birds have attained their wonderful multiplicity and diversity of 

 forms in Austro-Columbia and Australasia simply in consequence 

 of the very favourable nature of the conditions to which they have 

 been exposed in that country. 



"I confess I incline to the latter supposition. The distribution 

 of Psittacula, for instance, is quite unintelligible to me upon any 

 other supposition than that this genus existed in the Miocene 

 epoch, or earlier, in Northern Arctogaea, and has thence spread 

 into Austro-Columbia, South Africa, India, and the Papuan 

 Islands, where it is now found." 



Although the term Psittacula has now been restricted so as to 

 include only the Neogaeic forms, this passage is almost prophetic ; 

 both parrots and pigeons having, as already stated, been dis- 

 covered in the French Oligocene, while the Australian and 

 probably the South American ratite birds appear to have had an 

 Indian forerunner. And here it may be mentioned that the 

 South American ostriches (Rhea] which are primitive types allied 

 to the ostrich, would seem to have made their way into Neogaea 

 via Africa, as there are no traces of ancestral forms in the North 

 American Tertiaries. 



On the other hand, there is considerable probability that the 



1 Appendix, No. 18, p. 319. 



