8 THE STORY OF THE BIRDS 



most significant demonstration of the wonder- 

 ful progress of avine evolution. Two of the 

 most remarkable types of this era are Phoro- 

 rhacos and Brontornis. These avine giants are 

 from the Miocene deposits of South America. 

 These, together with several other genera (in all 

 we believe eight or nine are recognised), com- 

 prise what shortly after their discovery was 

 supposed to be an absolutely new order of birds 

 to which the name Stereornithes was applied, 

 but which subsequently was declared to possess 

 no such taxonomic importance. These very 

 wonderful bird remains, the existence of which 

 was only discovered a decade ago, appear to 

 indicate a rich avifauna in South America even 

 at that remote era, and form evidence of a most 

 significant kind relating to the dispersal of life 

 over the globe. The most remarkable feature 

 of these birds is the enormous size and massive 

 structure of the head, in comparison with the 

 limbs, although some of these are of gigantic 

 proportions. Probably we never shall have any 

 but the faintest idea of what these bird 

 monsters were actually like in fife, but that 

 they must have presented a most impressive 

 appearance with their huge laterally compressed 

 and hooked beak, cannot be doubted. That 



