E. LÖNNBERG, ON THE RHAMPHOTHECA OF BIRDS. 485 



according to my opinion an excessively enlarged internasal 

 or frontonasal. The nasal region appears to be soft in the 

 Cassowary too. 



The rhamphotheca of the Emeu (Dromceus) is conrposed 

 of the same pieces as that of the Cassowary with the excep- 

 tion that the internasal region is not developed to a casqne. It 

 is, however, more thickly horny than the same of the Nandu. 



In the Ostrich a similar condition prevails. The upper 

 jaw has a rostral and on either side two labials. The inter- 

 nasal is weakly developed, similar in shape to that of the 

 Nandu. It is, however, probably softer, so that it almost 

 makes the impression of a cere at the base of the bill, but 

 only having dry material I do not want to express any defi- 

 nite opinion about this. It may, however, be noticed that 

 this undoubtedly homologous part of the upper rhamphotheca 

 shows such a series of different degrees of development from 

 the strongly excessive one in the Cassowary to the probably 

 retrograde in the Ostrich. 



The lower rhamphoteca in the Ostrich shows a well 

 developed mentale and on either side two longitndinal shields 

 which may be regarded as an infralabial and a submandi- 

 bular. In the young of the Ostrich the limits of these two 

 shields are very pronounced as down grows between them 

 to a considerable distance from their posterior ends. 



Trom these statements it becomes apparent that the bilis 

 of the Nandus, Emeus, Cassowaries and Ostriches are essen- 

 tially alike in their structure. From this cannot, naturally 

 enough, be drawn any conclusion as to the monophyletic 

 origin of these birds. But on the other hand it is less than 

 probable that the compound bilis with their so closely 

 corresponding different parts are products of convergence. 

 Therefore the conclusion presents itself that all the birds 

 mentioned are derived from ancestors the bilis of which still 

 remained on the same primitive semireptilian x stage with 

 separate, not fused, horny shields probably arranged in a 

 manner not much aberrant from the now living birds describ- 

 ed above. These birds have consequently a great phyloge- 

 netic age essentially the same for all of them, and none of 

 them can be proclaimed as derived from »cranes» or other 

 more recent types through a retrograde development. 



1 That is with regard to the structure of the bill. 



