PHYLOGENY OF THE PLZOGNATHA AND NEOGNATH. 183 
In Dromwus the beak is flattened dorso-ventrally. The premaxillary body is larger 
than in Casuarius, and, as in this genus, the rod-like nasal process seems to be 
continued forwards to the tip of the beak by reason of paired lateral grooves which 
divide it from the maxillary processes. 
The nasal process is relatively longer than in Caswarius. Posteriorly it is received 
into a shallow groove excavated out of the median borders of the nasals. The tip of 
its free end rests upon the mesethmoid. 
The maxillary processes are splint-like, and extend backwards to the level of the 
anterior region of the orbit——beyond the body of the lachrymal. 
The palatine processes are short pointed lamellz, rather more widely separated one 
from another in the middle line than in Casuarius. ‘The chink-like anterior palatine 
foramen is closed caudad, as in Caswarius, by the vomer. ‘This process extends 
backwards as far as the level of the anterior border of the posterior narial aperture. 
In Casuarius, it should be mentioned, it falls short of this. 
In Dinornis the median nasal process is markedly flattened and expanded dorso- 
ventrally. ‘The maxillary processes are very short, not extending backwards beyond 
the level of the hinder end of the antorbital fossa. 
The palatine processes take the form of flattened amine, extending backwards, as in 
Dromeus, to the level of the anterior end of the posterior nares. The alveolar borders 
are deeply pitted. 
The anterior palatine foramen is small and cordiform. It is closed above by the 
parasphenoid rostrum, and posteriorly by the vomer. In Emeus it is more completely 
closed than in any other Palwognathe by a pair of processes from the postero-internal 
angles of the palatine processes, which meet in the middle line, serving at the same 
time as articular surfaces for the anterior ends of the probably paired vomers. 
The prenarial septum is most clearly marked in Dinornis. Its postero-ventral 
border is bilaminate, but the laminz rapidly fuse to form the single median vertical 
septum. 
In Aipyornis the nasal process rises sharply from the body of the bone, giving the 
beak a peculiar conical form. The alveolar border is deeply pitted. The backward 
extensions of the palatine and maxillary processes cannot be made out in either 
the British Museum skull or that belonging to the Hon. Walter Rothschild. In the 
British Museum skull there is a prenarial septum, but the lamin composing this 
have not fused to form a median plate as in Dinornis. Instead, as indicated, they 
remain widely separated, and enclose between them a long tunnel-like cavity extending 
forwards to the tip of the beak. 
In Rhea the premaxillary body is of greater length than in any other Ratite, and 
much depressed dorso-ventrally. It is grooved dorsally on either side of the distal end 
of the nasal process, as in the other forms. 
The nasal process is very broad and flattened, but tapers more or less caudad 
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