210 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
the hinder cervical and thoracic vertebre there is a large aperture beneath the 
diapophysis, opening in the roof of the tunnel for the vertebral artery, or in the thoracic 
vertebra below the prezygapophysis and between the dia- and parapophysial articula- 
tions of the tuberculum and capitulum. The deep fossa at the base of the anterior 
border of the neural spine of the hinder thoracic vertebra is here very shallow. 
In Rhea the vertebre have departed still more from the normal type. The cervicals 
are very long and cylindrical. Neural spines are present only on the 2nd to 5th 
vertebree. ‘The free hinder borders of the postzygapophyses of the 6th vertebra are 
received into a pair of shallow pits on the 7th, lying mesio-caudad of the prezyga- 
pophyses. Cervical ribs are only feebly developed. From the 2nd to 11th vertebre 
they are represented only by short styliform processes; from this vertebra backwards 
they are represented only by the extreme anterior articular end of the rib which serves 
to form the band-shaped external wall of the vertebrarterial canal. As in Struthio, the 
vertebrarterial canal is roofed by a backward extension of the lamelliform plate 
depending from the diapophysis and serving as an articulation for the cervical rib. 
This plate is described and figured as the “rudimentary rib” by Mivart [63]: 
doubtless by a slip. 
In Apterya the form of the atlas and axis vertebre bears some resemblance to 
Dromeus. The rest of its vertebra differ conspicuously from those of the forms 
herewith associated. The neural spines never bifurcate. On the anterior vertebre 
they form compressed blades from the Sth to the 12th; they are columnar and 
vertical in form and central in position with regard to the neural lamine. The 
diapophyses of the 6th and 7th vertebra project outwards and backwards beyond 
the level of the prezygapophysis; from the 7th to the 13th backwards and down- 
wards ; from this vertebra caudad they project directly outwards, and merge gradually 
into the transverse processes of the thoracic vertebre. The neural spines of the 
thoracic vertebra are equal in size, of great breadth antero-posteriorly, and interlock 
along the dorsal ridge by anterior and posterior bifurcations as in many Weognathe. 
There are no pneumatic apertures in either cervical or thoracic vertebra. Cervical 
ribs are vestigial. 
In Crypturi the thoracic vertebree are anchylosed and bear hypapophyses. In the 
Paleognathe these occur only on the posterior cervicals (cervico-thoracic). The 
penultimate is free, the ultimate fused with the synsacrum. The interzygapophysial 
ridge is perforated by pneumatic apertures. In the cervical vertebrae pneumatic 
apertures open into the roof of the vertebrarterial canal. 
The diapophyses of the cervicals project forwards beyond the prezygapophyses. 
The neural arch is constricted in the middle, immediately behind the prezygapophyses. 
The vertebrae of Dinornis resemble those of Casuarius. The fosse lying beneath 
the transverse process of the thoracic vertebra, absent in Dromeus, were much larger 
relatively than in Caswarius. The cervicals resembled those of some species of 
