AXIAL SKELETON OF THE PELECANUm 359 



spine is much more extended antero-posteriorly, while its hypapophysis is much reduced 

 (not being larger than in Phalacrocorax}, but still extending postaxiad of the centrum. 

 The rib-like styloid process is still shorter and more notched preaxially; while the 

 lamella of bone enclosing dorsally the lateral vertebral canal is still more antero- 

 posteriorly extended, and also more outwardly. The ventral surface of the centrum is 

 flattened and much broader than in the sixteenth vertebra, while its external margins 

 are developed with lateral catapophysial ridges. 



The EIGHTEENTH VEETEBEA (Plate LVIII. figs. 37 & 38) is like the seventeenth, except 

 that the neural spine is still more elongated antero-posteriorly, and dorsally flattened, 

 and the hypapophysis still more diminished, the centrum still more flattened beneath, 

 and its lateral ridges more developed. While the lamella enclosing the lateral canal 

 dorsally is as large, there is ventrally but a slender osseous bridge, the point of junc-> 

 tion between which and the dorsal plate is the last rudiment of the styloid process. 



THE CERVICO-PORSAL VERTEBRA, 



In the NINETEENTH VERTEBRA, compared with the eighteenth, the transverse processes 

 extend less outwards and are inclined more postaxiad, and the lateral hypapophysial 

 ridges are more developed, while the root of the median hypapophysis extends further 

 preaxiad (Plate LVIII. figs. 39 & 40). 



Compared with the nineteenth vertebra of Phalacrocorax, the transverse processes 

 extend much less outwards, the hypapophysis is much more postaxially situated, and 

 more inclined postaxiad distally. The centrum is very much less laterally compressed, 

 and very much more flattened ventrally, with lateral hypapophysial ridges much more 

 laterally extended ; these ridges cannot be parapophysial, because the heads of the ribs 

 articulate dorsally to them. The postaxial articular surface "of the centrum is much more 

 extended transversely; and the prgezygapophyses are relatively as well as absolutely 

 smaller. 



In the TWENTIETH VERTEBRA (Plate LVIII. figs. 41-43), compared with the nineteenth, 

 the lateral hypapophysial plates (or catapophyses) are still more developed externad, 

 being conspicuous lamellar processes. They do not, however, now reach to the post- 

 axial end of the centrum, but only project out from its preaxial half. The median 

 hypapophysis is shorter dorso-ventrally ; but its root now extends to the preaxial margin 

 of the centrum. The postaxial surface of the centrum is less extended transversely. 



Compared with the twentieth vertebra of Phalacrocorax, the median hypapophysis is 

 very small and postaxiad, while the centrum, instead of being greatly compressed 

 laterally, is extremely flattened ventrally with great lateral hypapophysial processes, 

 the distal ends of which begin to incline somewhat ventrad. The outline of the post- 

 axial articular surface of the centrum is more quadrangular, not rounded, and is less 

 concave. Its sides are concave from the outward extension of the postaxial ends of the 

 lateral hypapophysial ridges. 



