452 
part of the mouth-roof may be truly termed the maxillo-palatine part of that roof, 
including parts of both bones. In the skull of Dinornis ingens, figured in Plate LXXXII, 
fig. 3, a portion of the palato-maxillary suture still remams, and a smaller portion is 
traceable in the present specimen of D. crassus. 
Birds have the maxillary, 21, and palatine bones, 20, ossified, as in mammals, from 
separate centres, but have no maxillo-palatine bone, save by the accident of partial 
confluence. The specific palatal distinction from D. ingens appears in the course of the 
suture of the maxillo-palatine plate with the premaxillary. In D. ingens the suture 
runs across in an irregular wavy line; in D. crassus it presents an angular form, the 
maxillo-palatine plate being notched to receive the angular palatine process, 22’, of the 
premaxillary. 
In D. crassus, as in D, ingens and D, maximus, the slender part of the palatine, con- 
tinued backward from the palato-maxillary plate, is twisted so as to bring the inner edge 
of that plate downward, and to tun the horizontal under surface, 20, into a vertical 
outer surface of the bone, which rapidly gains in depth, and has its upper part bent 
inward, to complete with the vomer, 13, the hind wall of the palato-narial canal, At 
the outer and back part of the canal the palatine is thickened at its lower part to arti- 
culate with the pterygoid, 24. 
‘The yomer is bifid, as in J. ingens and as in the first-described skull of D. crassus 
(p. 266, Plate LXXVI.). The parial plates of the vomer overlap the sides of the 
presphenoids, 9, of which the anterior apex, 9! 
; coalesced with the narial septum, 
projects beyond the vomer, and partially divides the prepalatine vacuity. ‘The anterior 
ends of the halves are overlapped by the vomerine processes of the premaxillaries, 
Each half of the vomer consists of a deep vertical bony plate, almost meeting below the 
presphenoidal rostrum, expanding at both ends anteriorly to join the premaxillary 
aud the palato-maxillary plates, and there bounding the palato-nares anteriorly; pos- 
teriorly expanding in a greater degree, and curving outward and forward to join the 
palatines, and form the posterior boundaries of the palato-nares, These apertures are 
each 1 inch 7 lines in length, 55 hnes in breadth ; the breadth across both apertures is 
1 inch 113 lines, the additional half line giving the interval between the halves of the 
yomer, 
‘The suture between the vomer and palatine, as one looks down upon the skull's base, 
runs along the bottom of the vomero-palatine or postnarial fossa, along a shallow 
channel there ; it seems obliterated near the postero-external rather thickened border 
of that fossa, From this border the pterygoid process of the palatine is divided by a 
triangular shallow depression. The pterygoid bone, 24, is short, three-sided, with the 
sharp angle between the inner and outer facets of the under surface of the bone turned 
downward, and continuing backward a similar ridge on the under part of the palatine, 
The pterygoid has an extent of articulation with the tympanic of three lines in D, CYAS8Us, 
but one of more than half an inch in VY. maximus. The pterapophyses are marked a’, 
