XIII PHYLUM CHORDATA 443 



one order of Ratitge not found elsewhere; tlie Struthiones are 

 Ethiopian, but extend also into the adjacent part of the Palsearctic 

 region, the Rheae Neotropical, and the Megistanes Australasian. 

 jEpyornis, the affinities of which appear to be with the Megis- 

 tanes, occurs only in Madagascar, where it has become extinct 

 within— geologically speaking — comparatively recent times. 

 Taking the scattered distribution of the above-mentioned Raticas 

 into consideration, one of the most remarkable' facts in distri- 

 bution is the occurrence, in the limited area of New Zealand, of 

 no fewer than six genera and between twenty and thirty species 

 of Dinornithidse or Moas, some of which became extinct so short 

 a time ago that their skin, flesh, feathers, dung, and egg-shells 

 are preserved. 



Among the Carinatse the Penguins are exclusively southern, 

 occurring only in the South Temperate and Arctic Oceans. They 

 may be said to be represented in the Northern Hemisphere by the 

 Puffins and Auks, one of which, the now extinct Great Auk or Gare- 

 fowl (Alca impennis) was actually impennate, its wings being con- 

 verted, as in the Penguins, into paddles. The Crypturi (Tinamous) 

 are exclusively Neo-tropical, the Humming-birds American, the 

 Birds of Paradise and Bower-birds Australian and Austro-Malayan. 

 Amongst negative facts, the Psittaci or Parrots are characteristic- 

 ally absent in the Palsearctic and most of the Nearctic region, the 

 Finches in the Australasian region, as well as in New Zealand and 

 Polynesia, and the Starlings in both regions of the New World. 



Birds are comparatively rare in the fossil state : their powers of 

 flight render them less liable to be swept away and drowned by 

 floods and so embedded in deposits at the mouths of rivers or in 

 lakes. Up to the Cretaceous period, Archaeopteryx, from the 



-Lower Jurassic, is the only Bird known. In the Cretaceous of 

 North America toothed Birds of the orders Odontolcse and 



Ichthyornithes make their appearance, while in the Eocene 



numerous interesting forms occur, including the Gastornithes and 



the Stereornithes. 



Ethology. — It is impossible here to do more than allude, in the 

 briefest way, to the immense and fascinating group of facts relating 

 to the instincts, habits, and adaptations found in the class Aves. 

 Their social instincts, their song, their courtship-customs, the 

 wonderful advance in the parental instinct, leading to diminished 

 mortality in the young, are all subjects for which the reader 

 must be referred to the works on general Natural History men- 

 tioned in the Appendix. The same applies to the puzzling 

 subject of migration, which will be referred to in the Section on 

 Distribution. 



Fhylogeny. — That Birds are descended from Reptilian ances- 

 tors, that they are, as has been said, " glorified Reptiles " seems 

 as certain as anything of the kind can well be. Apart from the 



