PHYLOGENY OF THE PALZOGNATHZ AND NEOGNATH. 195 
surface for the external condyle of the quadrate is cup-shaped. ‘The internal and 
external angular processes are feebly developed. 
In khea the form and disposition of the articular surfaces agree with those of 
Dromeus. The internal angular process is large. ‘The symphysis is very broad. The 
ramus bears a small, perforate posterior lateral vacuity. 
Struthio in the form of its mandible rather closely resembles Dromeus. It differs, 
however, in its greater relative slenderness, in that it is sigmoidally curved, in the 
greater relative size of the expanded posterior portion, and in the elongated form of 
the articular facet for the external condyle of the quadrate. 
Epyornis also resembles Dromeus. The rami are, however, more laterally com- 
pressed, have an elongated anterior lateral vacuity, a broad dentary border, and the 
articular facet for the internal condyle of the quadrate situated at the bottom of a deep 
cup. The internal angular process is well developed and bears a large pneumatic 
foramen. 
In Crypturi the mandible resembles that of Rhea. The posterior angular process is, 
however, longer in Tinamous, and the posterior lateral vacuity appears to be wanting. 
Apterysx differs from all the other forms in the great length of the symphysis, which 
is about half the length of the ramus. The internal angular process is well developed. 
The coracoid in all the Paleognathine forms is small and rod-shaped. Sometimes, as 
in Struthio, it is reduced to a mere vestige. The dentary suture is always distinct. 
The Hyoid. 
Except in Apteryx, only the cerato-branchials appear to ossify in the Paleognathine 
forms. Epibranchials and the true hyoid elements appear to remain permanently 
cartilaginous. In Apteryx the basihyal appears to ossify at least occasionally. 
Tue SKULL OF THE NESTLING. 
The Cartilage-bones. 
The youngest of the Paleognathine skulls in my possession is that of an embryo 
Dromeus. The cartilage-bones are in all the stages herein described completely 
ossified. 
The basi-occipital, in the young Dromeus mentioned above, is perfectly distinguishable 
from the neighbouring bones (Pl. XLIII. fig. 5). 
It is bounded antero-laterally, and in front, by the basi-temporal plate of the para- 
sphenoid, and postero-laterally by the exoccipital. It is produced caudad to form 
the median portion of the occipital condyle. It is interesting to note, however, that 
it forms only the ventral part of this. It is entirely shut off from the occipital foramen 
