AXIAL SKELETON OF THE OSTRICH. 421 



THE LUMBAR VERTEBRA. 



The Twenty-eighth Vertebea. 



This is hardly to be distinguished in the adult, save by its transverse processes, which 

 are strongly inclined postaxiad and dorsad, and are the first, since the axis, which 

 present no indication of a rib. 



The under surface of its centrum is transversely concave (fig. 73). 



From the immature condition it may be seen that the spinous process is again higher, 

 that the diapophysis inclines outwards and dorsad and is ventrally continuous with the 

 parapophysis, that there are no postzygapophyses, but that its neural arch joins that of 

 the twenty-ninth vertebra by suture (fig. 58, 28). 



LATERAL ASPECT OF TWENTY-SEVENTH AND TWENTY-EIGHTH VERTEBRAE. 



Fig. 58. 



Letters as before. 



The Twenty-ninth Vertebra. 

 This vertebra (figs. 59, 60, & 61, i) like the preceding, but with a slightly higher 

 spine, more vertically extended transverse process, and no zygayophyses. 



The Thirtieth Vertebra. 

 This vertebra (figs. 59, 60, and 61, 2), as indicated by the young condition, has its 

 spinous process yet higher ; its diapophysis is also more dorsally produced, so that with 

 the conjoined parapophysis there is presented an elongated vertical surface for the ilium. 

 Without zygapophyses its neural arch is united to its centrum only by suture, and does 

 not extend postaxially so far as the latter, thus leaving a large intervertebral opening 

 between it and the ventral part of the neural arch of the next vertebra (fig. 59). 



The Thirty-first Vertebra. 

 This vertebra (figs. 59, 60, & 61, 3) has a spinous process slightly more elevated, and 

 even in the immature condition (fig. 59, 8) has this process anchylosed with that of the 

 next postaxial vertebra. 



