14 MR. ST. GEORGE MIVART ON THE 
The ninth rib articulates with the twenty-third vertebra, and seems to correspond 
with the tenth rib of Struthio. Being more preaxially directed, it diverges more from 
the eighth rib than does the tenth from the ninth in Struthio. It is also more equal to 
its predecessors in length than is either the ninth or the tenth of the last-named genus. 
The preaxial prominence is again very marked, but there is no preaxial concavity distal 
to it. The rib is more flattened than is either the ninth or the tenth of Struthio, and, 
once more, it is more curved. 
THE STERNAL RIBS (fig. 1). 
Of these there are apparently but three. It may be that a minute one exists pre- 
axiad of these three; but, if so, it is not to be found in the specimens examined. 
The first sternal rib seems to answer to that described as the second in Struthio. It 
is rather longer than the second vertebral rib, but is not so slender as the corresponding 
one in Struthio. Its outer surface is convex; its inner surface is flattened. It joins the 
fourth vertebral rib, and belongs to the eighteenth vertebra (fig. 1, 1). 
The second rib has its proximal end quite rounded; otherwise it resembles the third 
sternal rib of Struthio (fig. 1, 11). 
The third rib does not exceed the first in length by half the length of the latter. 
Its distal end is absolutely less expanded dorso-ventrally than is that of the second rib. 
Its postaxial surface is hardly more excavated than is that of the second rib. In other 
respects this bone resembles the fourth sternal rib of Struthio (fig. 1, 111). 
THE STERNUM. 
STERNUM OF RHEA (3 natural size). 
ce 
ca 



fl 



pit ie ii 
A i 
t} i i 
i 
iff 

Fig. 10. Ventral yiew. Fig. 11. Lateral view. 
cc, coracoid grooves ; ca, costal angles; f, median yentral prominence; 7, a yentral articular surface; s, a dorsal 
articular surface ; x, lateral xiphoid processes, 
