STRUCTURE AND CLASSIFICATION OF BIEDS 



forgotten that Dinoniis, like other ratites, except Apteryx, 

 has a single head to the quadrate. In the characters of the 

 pelvis Diiiornis is near to Apteryx and theCasuariid.se and 

 remote from BJiea (as well as from Struthio). The large 

 aftershaft allies it to the Casuariidse. NATHUSIUS has 

 commented upon the practical identity in egg-shell structure 

 which Rhea shows to Dinornis, a likeness which impressed 

 him so greatly that he proposed to place them in the same 

 genus. A considerable number of the special relations 

 between Apteryx and the Dinornithidae, upon which FTB- 

 BBINGEE writes, such as failing pneumaticity, absence of 

 clavicle, mutual distance between coracoids, and even the 

 form of the sternum, may largely depend upon the loss of 

 flight, which is more complete in these birds than in the 

 ostrich, for example. In no less than three footnotes 

 FUBBEINGEE comments upon the supposed absence of 

 uncinate processes to the ribs of the Dinornithidae ; but 

 this difference from other ratites does not exist, as T. J. 

 PAEKEE has definitely asserted their presence. It is signi- 

 ficant that in his tables of differential characters FUBBEINGEE 

 refers little to those of the fore limb girdle (including 

 sternum) as distinguishing Dinornithidae from Rkea. A 

 detailed account of the pros and cons will be found in the 

 systematic part of FUEBEINGEE' s work, and as regards the 

 skull in PAEKEE 's paper already referred to. 



The Struthiones have been often held to be more primitive 

 than any of the existing groups of birds. 



There are really, however, not a large series of characters 

 in which they may be fairly said to be more primitive 

 than some other groups, and most of these are shared by 

 some others. 



The form of the palate and the single-headed quadrate 

 appears to be a low character ; but the former is shared 

 with the tinamous, the latter with some other groups. The 

 incompleteness of the fusion of the cranial bones may be 

 looked at in the same way ; but the penguin is on the same 

 level as the Struthiones. The absence of any fusion distally 

 between the bones of the pelvis in Apteryx and Dinornis is 



