OF THE PALATE OF THE NEOGNATOR. 305 
and vomer, however, have been affected by this movement there 
can be no doubt, since, as I have pointed out, in many cases it 
has brought about the suppression or atrophy of the hemiptery- 
goid element, and has assumed the functions thereof by taking 
up the support of the vomer, as in the Anseres and Falconide. 
The most primitive form of Avian palate is most certainly the 
Dromzognathous, not, as has been stated, the Schizognathous. 
The Schizognathous and A®githognathous palates’ are both 
specialized forms derived by modification of the Dromeognathous 
type. The Desmognathous palate is a highly specialized con- 
dition which appears to have arisen independently amongst both 
Schizo- and Aigithognathous forms. 
The Neognathine palate is undoubtedly undergoing a further 
change, a change resulting in the transference of the support of 
the vomer from the pterygoid to the palatine. This has followed 
upon the movement of the palatines from the original position 
outside the pterygo-vomerine bar to a position beneath this. 
But the disturbance does not end here, for it is in the most 
highly specialized forms accompanied by the degeneration of the 
distal end of the pterygoid and the suppression of the vomer. 
EXPLANATION OF THE PLATES. 
Puate 31. 
Fig. 1. Ventral view of the skull of Dromeus nove-hollandia, showing the most 
pvimitive arrangement of the palatal bones among living birds. The 
vomer is of great size, and extends backwards in the form of a pair of 
broad limbs beneath the laminate, pointed pterygoid. The palatines 
are connected by suture, posteriorly with the external lateral vomero- 
pterygoid border, anteriorly with the maxillo-palatine process. 
Fig. 2. The palate of Rhea americana. The vomer has relatively decreased in 
size. Its relations with the pterygoid are much the same as in 
Dromeus; but this fact is masked by the palatines, which have- 
moved inwards beneath the pterygo-vomerine articulation so as to 
approach one another in the middle line. The palatine, as in 
Dromeus, is connected by suture with the maxillo-palatine process. 
anteriorly. It is interesting to note that the posterior narial aperture 
of hea has been largely filled up by the inward and backward ex- 
tension of the maxillo-palatine precess. In Dromeus this aperture is 
very large. ‘The premaxillary processes of thea are also very large. 
Fig. 3. The palate of Nothoprocta perdicarius. Compared with Rhea, it 
will be seen that the vomer is, relatively, still further reduced, and 
that the palatines have moved still further inwards beneath the- 
LINN. JOURN.—ZOOLOGY, VOL. XXVIII. 25 
