AXIAL SKELETON OF THE PELECANID A. 323 
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This vertebra unites with the seventh at a marked angle, but one which opens the 
reverse way from that in which the angle formed by the seventh with the sixth ver- 
tebra opens. The mode of flexion here initiated is repeated in the next articulation ; 
so that the eighth vertebra has both its adjacent vertebree bent up dorsad from it, 
whereas the third, fourth, fifth, and sixth vertebre have each their two adjacent 
vertebree bent down ventrad, while the seventh vertebra has its next preaxial vertebra 
bent down ventrad from it, and its next postaxial vertebra bent up dorsad from it. 
The NINTH VERTEBRA (Plate LV. figs. 18-21) is very like the eighth, but slightly longer. 
The preaxial articular surface of the centrum is directed somewhat more dorsad and less 
preaxiad, and is alittle more transversely extended. The preaxial openings of the canals 
for the vertebral artery are even more plainly visible when the vertebra is viewed dorsally 
(fig. 19). The articular surfaces of the preezygapophyses are directed more mediad ; and 
the processes supporting these surfaces are seen to extend postaxiad as well as dorsad 
when the vertebra is viewed laterally. The constriction (laterally) of the neural arch by 
the fossee just postaxiad of the preezygapophyses is more marked. The hyperapophyses 
are similarly but more developed. The preaxial margin of the hemal (catapophysial) 
arch extends as much preaxiad as does any part of the centrum. 
The plates bounding laterally the median subcentral groove do not end in such 
distinct processes, the ventral margin postaxiad of each such process sloping more 
obliquely to reach the postaxial end of the centrum. 
The TENTH VERTEBRA is like the ninth, but slightly longer. ‘The hyperapophyses are 
less marked, except at their postaxial ends. The neural spine stops short of the post- 
axial end of the neural arch. ‘The postzygapophyses look more externad. ‘The hemal 
arch is more antero-posteriorly extended, and the grooves on its ventral surface are 
wider and deeper. The margins of the subcentral median channel subside gradually 
postaxiad without there being any longer a noticeable process. 
The ELEVENTH VERTEBRA, compared with the same vertebra in Struthio and Dromeus, 
presents striking differences. Thus the preaxial surface of the centrum looks dorsad 
instead of ventrad, and its postaxial surface looks postaxiad instead of partly dorsad. 
The preezygapophysial surfaces are differently directed, and are less long, relatively, than 
in Struthio; though not than in Dromeus. There are no styliform rib processes; but 
there is a hemal arch and subcentral channel. 
The whole vertebra is not so long a bone, in proportion to its other dimensions, as 
in Struthio; but it is longer relatively than in Dromeus. 
This vertebra is like the tenth of Pelecanus, save that it is stouter, though not 
longer. Its postaxial articular surface expands less ventrad. Its prezygapophysial 
surfaces lie more open, ¢.¢. look rather more dorsad. The hyperapophyses are less 
strongly marked ; and the neural arch is more flattened dorsally. The plates bounding 
the subcentral channel laterally, subside still more postaxially. The prezygapophyses 
(i.e. the processes supporting the articular surfaces) extend more dorsad and less post- 
VoL. X.—ParT vil. No. 2.— August Ist, 1878. 2Y 
