No. 433 ] CERTAIN GROUPS OF BIRDS. 



57 



for Struthio and Rhea; the other forks a second time, one 

 branch dividing again for Casuarius and Dromaeus, the other 

 for Dinornis and Apteryx. 



"The monophyletic origin of the Ratitae is also supported 

 by Newton, who, in his luminous article, ' Ornithology,' says 

 ' that these forms — moa, kiwi, emu and cassowary, rhea, 

 and finally ostrich — must have had a common ancestor nearer 

 to them than is the ancestor of any carinate form' seems to 

 need no proof. 



" Professor Newton's classification indicates no closer affinity 

 between any of the genera except the emu and cassowary, 

 which together constitute his order Megistanes ; each of the 

 other genera has an order to itself. 



" A study of the skull certainly confirms the view that the 

 nearest ally of the Dinornithidae is Apteryx, and that the four 

 families of Australasian Ratitae are more nearly related to one 

 another than is either of them to the Asio-African and South- 

 American forms. Struthio and Rhea differ so much from the 

 Australasian members of the subclass as to lend strong sup- 

 port to Fiirbringer's view that they arose separately from a 

 primitive stock ; but whether the cassowaries and emus on 

 the one hand and the moas and kiwis on the other had a dis- 

 tinct or a common origin is a very complex question. 



"The main difficulty lies in deciding what characters should 

 be considered as of phylogenetic importance and what merely 

 adaptive, but it appears to me that in the following particulars 

 the emu and cassowary show an undoubted relationship to the 



" The general characters of the maxilla, maxillo-palatine, and 

 antrum in both genera. 



" The general relations of the vomer, palatines, and pterygoids 

 in both genera. 



" The presence of a vestige of the maxillary process of the 

 nasal in Dromasus. 



"The well-ossified antorbital ankylosed to the descending 

 process of the lacrymal in both genera. 



1 " As my conclusions are based upon a study of the skull, T have omitted all 

 reference to ^Epyornis, Dromornis, Megalapteryx, and Palaeocasuarinus." 



