246 C. W. Andreios — ^pyornis from Madagascar. 



vertebrse are — (1) The neural or postzygapophysial ridges become 

 higher and at the same time do not extend so far forward. (2) On 

 the eleventh there are small paired hypapophyses on the ventral 

 surface of the centrum ; in the twelfth these unite, forming a low 

 median tubex'osity, which increases in height to the seventeenth, 

 behind which it also increases in antero-posterior extent, until on 

 twenty and twenty-one it forms a keel more than half the 1 ength of 

 the centrum. In all these vertebra the centrum is broad and the 

 articular faces much wider than high. 



On all the cervical vertebrge the fused ribs are very broad, and 

 enclose a large vertebrarterial canal. 



The next vertebra (21) is the first with a free rib, and both it and 

 the succeeding two may be regarded as cervico-dorsals. In these 

 the anterior portion of the neural ridges are united by a broad base 

 and again rise to form a bifid neural spine. In the last cervico- 

 dorsal, however (23), the basal portion of the spine increases in 

 height, while the bifid part is relatively smaller; in the next (24) 

 the spine is a massive quadrate structure, which shows only a trace 

 of the bifid condition at its upper end, and in the following 

 vertebrse it increases in height and antero-posterior extent. In all 

 the dorsal vertebrae the spine bears on its anterior, posterior, and 

 lateral surfaces vertical ridges, which in their lower portion expand 

 into thin buttresses of bone : of these the anterior runs forward to 

 the middle point of the anterior border of the neural arch, the lateral 

 outward to the diapophysis, the posterior, which is the smallest, to 

 the middle point of the posterior border of the arch. On 23-28 

 inclusive there is also a pair of postero-lateral buttresses which run 

 outward and backward on to the posterior zygapophyses ; in 23-26 

 these ridges terminate in a small hyperapophysis : they are 

 homologous with the posterior portion of the neural or post- 

 zygapophysial ridges. In all these vertebrae between the bases of 

 these plate-like buttresses there are deep pocket-like fossae. 



In the cervico-dorsal and dorsal series the diapophyses become less 

 massive and project farther laterally as we pass backwards, and 

 at the same time the pneumatic fossa occurring at their base 

 increases in size. In these vertebrae the an tero- lateral margin of 

 the centrum forms a prominent lip which bears a deep capitular 

 facet ; in the cervico-dorsals this is circular, in the dorsals it is 

 elongated from above downward and forward. These vertebrfe 

 have on their ventral surfaces prominent keel-like hypapophyses, 

 which in the posterior ones are directed forward and occupy almost 

 the whole length of the centrum. 



The first pelvic vertebra has a high massive neural spine, the 

 quadrate upper end of which is exposed between the divergent 

 anterior ends of the ilia. Its transverse process is single (dia- 

 pophysis), and unites with the ilia by its expanded outer end : it bears 

 a facet for the tubercle of the free rib, the head of which articulates 

 virith a facet on the anterior margin of the centrum. There is some 

 indication of a median hypapophysis, and both the side of the 

 centrum and the base of the diapophysis are perforated by large 



