150 PROFESSOR OWEN ON THE GENUS DINORNIS. 
atlas, and equals about 24 inches. The preaxial surface of the centrum (fig. 5, cx) is 
twice as broad as high, and is concave transversely, but less deeply than it is neuro- 
hemally. It is not prolonged neurally, as in the Ostrich, “on to each side of the 
AXIS, or SECOND, VERTEBRA (natural size). 

Aspects. 
Fig. 4, lateral: 5, preaxial; 6, postaxial ; 7, hamal (or ventral). 
base of the odontoid process”!; a slight non-articular concavity separates it on each side 
from the convex articular surface on the under part of the odontoid (figs. 4 and 7, 
: ont 
ca, 0). ‘This surface is convex, narrower, and more produced than in the Ostrich °. 
" Mivart, Joc. cit. p. 391. * Ibid. fig. 12, 0. 
