PHYLOGENY OF THE PALZOGNATHZ AND NEOGNATH#, 173 
in the form of this platform. In Dromeus ater it is very sharply defined, presenting 
a steep face to the pre-condylar fossa; in the other species of Dromeus and in Struthio 
this face slopes gently upwards and backwards. Thus, in all save D. ater, the pre- 
condylar fossa is shallow and moderately wide. 
The pre-temporal platform is very sharply defined in Avterya, Dinornithide, and Rhea. 
In Apteryx and Dinornithine amongst the Moas, it is roughly triangular in form, 
its postero-lateral angles are produced downwards into moderately or very large 
mammillary processes. ‘These in some of the Dinornithinw coalesce in the middle 
line, and present a deep vertical face when the skull is seen from behind. In the 
Emeine the platform takes a laterally expanded pentagonal form, sharply defined along 
its antero-lateral angles by a raised ridge helping to form the Eustachian groove. 
The anterior basicranial fontanelle is marked by a deep groove. In Apyornis the 
basitemporal platform is much shortened antero-posteriorly. The mammillary tubero- 
sities run in the form of a low rough ridge along the whole of each postero-lateral side 
of the pentagon. 
In Rhea the platform has the shape of an elongated pentagon presenting steep 
faces on all sides, though anteriorly it may slope gradually into the rostrum. The 
Eustachian apertures lie immediately below the bases of the basipterygoid processes. 
The Eustachian grooves are short, widely separated one from the other in the middle 
line, and, in all except Dinornis and Casuarius, arched over by bone. In these last the 
groove remains permanently open. In Rhea, Struthio, and Dromeus the mouth of the 
aperture of each is conspicuous, lying on either side of the base of the basipterygoid 
processes. In Apterya they lie nearer the middle line and are inconspicuous. In the 
Tinamous these apertures are very wide apart, opening immediately behind the basi- 
pterygoid processes. 
The paroccipital notch is more or less wide in all save Apteryx, where it is narrow 
and deep. As in Rhea, it is more or less completely bounded on its outer side by a 
much compressed, forwardly directed lamina of bone from the paroccipital process 
(p. 172). 
Within this notch, in Struthio, Rhea, Dromeus, Casuarius, Apteryx, and the Tinamous, 
occurs the vagus foramen for the ninth and tenth nerves, the condyloid foramina for 
the exit of the twelfth nerve lie behind it, between it and the occipital condyle. 
In the Dinornithine the vagus foramen occurs behind the notch and much nearer to 
the condyloid foramina, forming, with them, a little cluster of apertures, that of the vagus 
being much the longest of the group. ‘The carotid foramen in the Dinornithide@ lies 
immediately in front of the notch, in all the other forms it occurs some distance further 
forwards. 
Traces of both anterior and posterior basicranial fontanelles occur in many of these 
Paleognathine skulls, sometimes both are indicated in the same skull. The former 
is the small pit in the middle line between the anterior ends of the basipterygoid 
vou. xv.—Ppart y. No. 9.—December, 1900. 2c 
