168 Walter Rothschild. 



in connection herewith that at the time when Aepyornis, 

 Dromornisj Genyornisy Dlnornis, ApteryXj, &c. were first evolved, 

 both the New Zealand and the Mascarene Regions were enormousl}^ 

 larger than they are Jiow; the Mascarene Region extending at 

 least from the Seychelles in the North to the South End of 

 Madagascar in the South and from the island of Europa in the 

 South West to the Chagos Archipelago in the North East, while 

 New Zealand extended at least from Norfolk Island in the North 

 to Campbell Island in the South and from Lord Howe's Island 

 in the North West to the Chatham Islands in the South East. 

 It was only when much of these land masses disappeared that 

 the large number of forms become concentrated in Papua, New 

 Zealand, and Madagascar. 



From our knowledge of the former and present distribution 

 and also the anatomy of the various groups of Ratite Palaeo- 

 gnathae we cannot work out their ancestral Genealogical Tree 

 as completely as we could wish, but the following two or three 

 general conclusions can be safely drawn. 



1. That all the known Ratite Palaeognathae are descended 

 from ancestral forms capable of flight. 



2. That the various groups are not descended from one 

 ancestral stock but from several. 



3. Although our knowledge of fossil birds is comparatively 

 scanty we can deduce from it that the Ratite Palaeognathae did 

 not begin to develope to any large extent till very late; for 

 before the Pleistocene epoch the number of species is very small. 

 That this development took place in the Mascarene and Papuo- 

 Australasian regions on the largest scale is evidently due to the 

 comparative absence of enemies and the more suitable conditions 

 of existance. 



I should here like to remark that I use the generic term 

 Cela in the sense of Reichenbach and not in that of Moehring 

 who coined this word as a generic term or rather name for the 

 Cassowary. 



I also have altered the names of the two Jlheas for it is quite 

 certain that Linnaeus applied the name of Struthio americanus 

 to the North Brazilian Rhea which was afterwards renamed Rhea 

 viacrorhyncha by Dr. P. L. S dater. The all-familiar Argentine 

 bird therefore must be called by Lesson's name of Rhea nandù. 



I have so far only found records of two cases of hybrids 

 among the Ratitae. i'*"* I have bred myself a hybrid of Rhea 

 na7idu X Rhea dariuini and this same hybrid was hatched in the 

 Zoological Gardens London. The latter however did not live 

 more than a few days, Avhile my bird is fully adult and at present 

 sitting on 8 eggs of Fvhea darwini ? which if hatched will be 

 ^U Rhea darwini + ^U Rhea nandù. 2"** Hybrids are mentioned 

 between Rhea americana and Rhea nandù but I personally have 



