PHYLOGENY OF THE PALZOGNATHA AND NEOGNATH#, 263 
validity of my conclusions rather than his, for those who know his monographs on the 
development of Apteryx and the skull of the Dinornithide will agree that they are 
monuments which mark an epoch in the history of this subject. In his work on the 
skull of the Dinornithide he wrote: ‘‘'The marked differences between the Moas and 
Kiwis are certainly for the most part adaptive... .. The real affinities underlying 
these differences are, however, shown by the striking similarity of the bones of the 
palate in the two forms.” 
The skull of Caswarius, it may be remarked here, differs in no essential respect from 
that of Dromeus. In whatsoever it differs from Dromeus point to specialization, as, 
for instance, the development of the casque upon the mesethmoid (p. 199, Pl. XLIV. 
fig. 3) and the small quadrato-jugal fossa. 
The skull of Dromeus, it would seem, must be regarded as the most generalized of 
living birds, at least in so far as the bones of the palate are concerned. 
Struthio somewhat nearly approaches Dromeus in the arrangement of these bones, 
Rhea, the Tinamous, the Dinornithide, and probably the AYpyornithide agree more 
closely one with another than with Dromeus. 
Apteryx differs from all in the direction of increased complexity of these parts. 
We have now Struthio and Dromeus with Casuarius opposed to Rhea, Dinornithide, 
and Crypturi, and possibly A%pyornis. ‘These last we may further subdivide by 
means of the pelvis. ‘This will separate Rhea from the remaining forms; inasmuch 
as in Rhea the pelvis is long and narrow, with the post-acetabular ilia meeting in the 
middle line, as in Apteryx. 
In the Dinornithide, M@pyornis, and the Tinamous the post-acetabular ilia are 
separated by the long transverse processes of the synsacrum. 
It may seem that this character of the pelvis is a somewhat artificial one, but 
reflection will show, I think, that it is probably not so. It does not seem to belong 
to the category of adaptive characters, since Rhea and Apteryx in the general confor- 
mation of the pelvis agree, though their habits are very different, and both bear some 
similarity to that of Struthio—similar in so far as the great length and transverse 
width are concerned. In the Tinamidw, Dinornithide, and Afpyornis the pelvis owes 
its great breadth to (1) elongated transverse processes, and (2) the broad dorsal plane 
of the post-acetabular ilium. 
The pelvis of Struthio bears an undoubted resemblance to the Dinornithine form, 
inasmuch as, like Dinornis or Afpyornis, the transverse processes bear the post- 
acetabular ilia away from all contact with the neural spines of the synsacrum. 
Fiirbringer’s view with regard to the Dromeide is not exactly in harmony with 
the views adopted here, but it lends some support thereto nevertheless. He says 
Dromeus and Casuarius “bilden zwei sehr nahe verwandte Familien..... welche 
etwas hdher als die Struthionide, aber tiefer als die Rhetde stehen und im Ubrigen 
sowohl yon den anderen Ratiten ..... als von den Carinaten eine entfernte 
202 
