Present distribution of the so called Ratitae. 149 



omis. But llic anatomical characters of these flightless Eocene 

 forms under an\- circumstances could only show analogies and 

 certainly no direct relationship with the Pleistocene Cneiniornis. 



1 consider, in fact, these analogous structural resemblances of 

 minor importance and only indications of similar determining 

 evolutionary factors and mode of life. The large and long head 

 of Gastoniis and the teeth now known to have been present in 

 the mandible are no longer considered as indicating a herodian 

 and anserine type with teeth but a forerunner of a more Palaeo- 

 gnathiiìe ancestor of the Ratitae. Macrornis and Megalorniß 

 have been founded on jjortions of tibiae and are apparently more 

 allied to Drovmws in respect to that bone. 



Dasoniis is only known from a portion of a skull showing 

 dimensions and proportions similar to Dinornis maximus. 

 Laopterijx was described from a small portion of a skull indi- 

 cating a bird the size of a heron. Marsh declares that on the one 

 hand'it shows Raiite and on the other Reptilian affinities and a 

 loose tooth in the matrix shows that it was almost certainly 

 toothed. Barornis was described by Marsh from various pha- 

 langes of the digits of the right foot and he considered it showed 

 analogies to Dinornis. 



We thus know of these early forms 3 Genera and 3 Species 

 from North America; i Genus and 3 Species from South America; 



2 Genera and 2 Species form North Africa and 5 Genera and 

 7 Species from Europe. It is evident that in North America the 

 conditions were not the same as elsewhere for the Heterornithine 

 birds died out without either leaving any direct descendants or 

 evolving Ratite Palaeognathae. In South America we not only 

 have living Ratitae in the shape of the 3 species of Rliea but 

 also remains of at least 3 Pliocene species of Rhea are known, 

 all of which appear to be directly descended from Mesemhriornis. 

 When we come to Europe and North Africa another problem 

 arises: in Europe the H eterornithes have not yet been traced to 

 the region of the Mediterranean basin where undoubtedly the 

 direct ancestors of Struthio where evolved, so that we cannot, as 

 in the case of Mesemhriornis and Rhea, even guess at the ancient 

 form in Europe which gave rise to a Ratite form also long since 

 disappeared. In North Africa on the other hand the Eocene 

 forms Eremopezus and Fsamm,ornis had already acquired full 

 Ratite Palaegnathine characters of a general type intermediate 

 between Aepyoniis and Struthio, thus proving that the immediate 

 fore-runners of one of the ancestral forms of the old world Ratitae 

 were evolved in the southern Mediterranean basin and thence 

 spread northwards and eastwards as far as China. 



Up to the present time no Eocene remains of Heterornithine 

 birds are known from Asia or Australasia, so that we cannot 

 even guess at the probable ancestors or fore-runners of Dromornis, 



