326 PROF. ST. GEORGE MIVART ON THE 
The hypapophysis is much smaller than in the fifteenth vertebra, and springs from 
close to the preaxial margin of the centrum. 
A slightly marked ridge runs postaxiad and externad from a point mesiad of the 
parapophysial root of the bony bridge above described. These lateral ventral ridges 
are the serial representatives of the catapophysial ridges of more preaxial vertebre, 
and each ends postaxially in a small transverse process, which projects externad on a 
line just postaxiad to the whole. For the first time since the fourth vertebra, we here 
find the postzygapophyses extending postaxiad decidedly, though very little, beyond 
their articular surfaces. 
THE CERVICO-DORSAL VERTEBRA. 
The SEVENTEENTH VERTEBRA again exaggerates the character of its serial predecessor. 
The whole vertebra is antero-posteriorly shorter, and in fact somewhat smaller in 
nearly all dimensions; but the transverse processes and metapophyses (seen dorsally) 
are much as in the sixteenth vertebra. The zygapophyses are a little smaller. The 
neural spine is antero-posteriorly extended at its tip, whilst its postaxial fossa is so 
postaxial that it is invisible when viewed dorsally. The neural spine broadens out 
postaxially, exhibiting, dorsally, a median ridge and two lateral ones diverging from a 
common point postaxiad. 
The hyperapophyses project as two little pointed processes, one above each postzyg- 
apophysis. ‘The preaxial articular surface of the centrum widens out still more, and 
looks entirely preaxiad, or only very slightly indeed ventrad. The postaxial central 
surface looks postaxiad. 
The hypapophysis is smaller, and the ridges on each side of its root fainter. 
There is no lateral vertebral canal. Such a canal is inclosed only by the help of the 
rib; and to support this there are two distinct articular facets—a parapophysial one a 
little postaxiad of the lateral margin of the preaxial articular surface of the centrum, 
and another diapophysial one beneath the postaxial end of the antero-posterior ridge of 
the transverse process. 
The preezygapophyses do not project so far preaxiad as does the centrum. 
The seventeenth vertebra is in one line with the eighteenth. 
Tue DorsaL VERTEBRE. 
The EIGHTEENTH VERTEBRA is slightly smaller than the seventeenth. The preaxial 
surface of the centrum is less wide transversely; the same is the case with its postaxial 
surface, which is also not at all concave at its ventral margin. The hypapophysis is 
rudimentary and has no ridges on each side of its root. ‘The transverse process is 
somewhat less produced postaxially. The neural spine and its postaxial fossa are both 
smaller. The prezygapophyses fall still further short of attaining the preaxial end of 
the centrum, while the postzygapophyses extend rather less postaxially beyond the 
