14 



ME. ST. GEORGE MIVAUT 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 EIBS (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 frst 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, i). 



The second rib has its proximal end quite rounded ; otherwise it resembles the third 

 sternal rib of Struthio (fig. 1, ii). 



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, in). 



THE STERNUM. 



STERNUM OF RHEA (^ natural size). 

 Fig. 10. 



Fig. 10. Ventral view. Fig. 11. Lateral view. 



«, corscoid grooTes ; ca, costal angles ; /, median Tentral prominence ; i, a Tentral articular surface ; j, a doraul 

 articular surface ; /x, lateral xiphoid processes. 



