AXIAL SKELETON OF THE PELECANID^. 321 



series with the side of the median ventral prominence beneath the haemal arch of more 

 postaxial vertebrae. The parapophysial process of the seventh vertebra is much smaller 

 and less conspicuous than in the sixth vertebra, and is a little antero-posterior ridge of 

 bone outside the postero-ventral part of the pleurapophysial lamella. 



Thus the ridges bounding the median subcentral groove in more postaxial vertebrae 

 are catapophysial (i. e. lateral hypapophyses), the parapophysis hardly reappearing as a 

 small distinct process till the fifteenth vertebra. 



The diapophysis does not begin to appear as a more or less distinct, though small, 

 postaxially projecting process till at the fourteenth vertebra. 



When the seventh vertebra is viewed dorsally, the hyperapophyses are seen to have 

 advanced somewhat preaxiad from the ends of the postzygapophyses, which extend 

 much outwardly and postaxially beyond them. 



The EIGHTH VERTEBRA, unlike the same vertebra in Struthio and Dromceus, presents 

 very great differences from its preaxial predecessor. The latter differs strikingly from 

 the sixth by the sudden appearance of a deep concavity at the postaxial margin of the 

 neural arch between the long backwardly extending postzygapophyses ; but in the 

 eighth vertebra other and more remarkable characters suddenly appear, some of which 

 are correlated with the backward extension of the postzygapophyses of the seventh 

 vertebra (Plate LV. figs. 13-17). 



The eighth vertebra is slightly shorter than the seventh, and very slightly shorter 

 than the sixth, fifth, or even the fourth vertebra, though it is longer than the 

 third. 



When the eighth vertebra is viewed dorsally the neural surface of its centrum is 

 more exposed than in the seventh vertebra through the oblique cutting away of the 

 preaxial part of its neural arch, which arch is deeply concave postaxially, even more so 

 than in the seventh vertebra (fig. 14). 



The preaxial articular surface of the centrum (fig. 16) looks preaxiad and somewhat 

 dorsad (instead of almost entirely ventrad, as in the preceding vertebra), is very much con- 

 stricted medianly, while each lateral and expanded part is very convex dorso-ventrally, 

 and very slightly indeed concave transversely. The preaxial opening of the vertebral 

 lateral canal (v) opens above (dorsad) and postaxiad to this surface, instead of above and 

 beside it as in the seventh vertebra ; thus it is hardly seen when the vertebra is viewed 

 preaxially, but is conspicuous when the vertebra is viewed dorsally conditions pre- 

 cisely the reverse of those obtaining in the seventh vertebra. 



The postaxial articular surface of centrum (fig. 17) expands more laterally ventrad than 

 in the seventh vertebra ; and the whole surface looks postaxiad and not dorsad. Viewed 

 laterally the vertebra is seen to be less bent ventrad at its postaxial end than in the 

 seventh vertebra, and the postaxial end of the catapophysial ridge, or plate (which 

 bounds the subcentral groove externally), is more sharply defined as a process. 



For the first time since the axis vertebra, the praezygapophyses are not carried pre- 



