C. W. Andrews — ^pyornis from Madagascar. 245 



The third vertebra, seen from above, has the usual quadrate form, 

 but the width is greater than the length as in Dinornis, instead of 

 the reverse as in Struthio. The anterior articular face of the 

 centrum looks completely downward ; it is much narrowed in the 

 middle by a fossa which forms a deep emargination in its hinder 

 border. The posterior articulation is similar to that of the axis, but 

 wider in proportion to its height. The ventral surface, deeply 

 concave from side to side in front, becomes narrower posteriorly 

 and bears a hypapophysial keel. The anterior and posterior 

 zygapophyses are both large and nearly equal in size, and there 

 are large hyperapophyses over the posterior ones. The inter- 

 zygapophysial bar is broad and there is an interzygapophysial 

 foramen. The neural spine consists of a broad basal platform, 

 increasing in height posteriorly and bearing on its posterior surface 

 a pit for ligament. Superiorly it is bifid, rising into two prominent 

 tuberosities separated from one another by a deep groove. Between 

 these processes and the hj'perapophyses there is a broad valley. 



The fourth vertebra is very similar to the third, except that the 

 posterior articulation of the centrum is broader. The fifth is also 

 similar, but the neural spine is rather higher. In vertebra 4-6 the 

 anterior zygapophyses look upward and forward, making an angle 

 of about 45° with the long axis of the column ; they are not directed 

 at all inwards. In the sixth the transverse bar of the neural spine 

 is reduced, while its bifid extremity increases in height ; at the same 

 time the spine is shifted towards the anterior border of the neural plat- 

 form, which here commences to increase in length ; the hyperapophyses 

 are much smaller, and the interzygapophysial bar is reduced. In 

 the centrum the articular surfaces are much broader than high, and 

 the hypapophysis is reduced to a small ridge near the middle of 

 the ventral surface. The seventh is similar to the sixth, but shows 

 traces of the narrowing of the posterior region of the neural 

 platform, which is the most remarkable character of the eighth.^ 

 In the eighth the anterior half of the neural platform is more than 

 twice as wide as the posterior. The neural spine, as before, consists 

 of a basal portion bearing a bifid extremity ; but it is farther 

 forward and is united on either side to the hyperapophysis by an 

 oblique ridge. The posterior zygapophyses now look outward as 

 well as downward and backward. The centrum is very broad, and 

 there is no trace of a median hypapophysis. In the ninth, the 

 neural spine is represented only by the anterior portion of the ridges 

 (neural or postzygapophysial), which run forward from the hypera- 

 pophyses, converging towards the middle point of the anterior 

 margin, where they meet in a slight prominence ; in the angle 

 between these ridges there is a deep pit for ligament. Behind the 

 anterior zygapophyses there is a pocket-like fossa, into which open 

 pneumatic foramina. 



The next ten vertebra resemble the ninth in general character. 

 The chief modifications that are perceptible in the successive 



1 It may here be remarked that it is possible that a Yertebra too many may haye 

 been used in reconstructing this anterior portion of the neck. 



