322 PROF. ST. GEORGE MIVART ON THE 
axiad but dorsad, and fail to project preaxially as much as does the centrum. The 
articular surface of each prezygapophysis looks not only dorsad and mediad, but, for the 
first time of all, even slightly postaxiad; it is convex antero-posteriorly, with a hardly 
perceptible concavity transversely. 
The postzygapophyses (7. e. the whole processes which support the articular sur- 
faces, not alone those surfaces themselves) extend more directly postaxiad, and more 
postaxiad of the centrum than in the seventh vertebra. The articular surface is less 
broad in proportion to its length antero-posteriorly, and looks more externad and less 
ventrad than in the seventh vertebra. The neural spine is much less prominent. 
The metapophysis (m) appears as a slight prominence outside the preezygapophysis. 
Seen dorsally (fig. 14), a marked fossa is visible on each side postaxial to (and as it 
were continued on from) the praezygapophysis. ‘These fosse receive the postzygapophyses 
of the seventh vertebra when it is much bent back upon the eighth vertebra. The 
hyperapophyses, seen thus, also exhibit a singular change from their condition in more 
preaxial vertebrae. In the seventh vertebra (as before said) they have already left the 
ends of the postzygapophyses and advanced preaxiad; but here they extend forwards 
as two oblique ridges, approximating preaxially, and about as prominent as is the 
neural spine. 
In P. rufescens they extend forwards over the postaxial two thirds of the neural arch. 
In P. onocratalus they extend yet considerably more preaxiad, and form the lateral 
margins of the neural arch when this is dorsally viewed. - 
The pleurapophysial lamella is shorter antero-posteriorly than in the seventh ver- 
tebra; there is no styloid or distinct parapophysial process of any kind; and the oval 
subcentral foramen is more or less visible, when the vertebra is viewed laterally, post- 
axial to the postaxial margin of the pleurapophysial lamella. 
The lateral vertebral canal runs very obliquely, and suddenly dorsad, as it extends 
preaxiad—in marked contrast to its course in the seventh vertebra. 
When the vertebra is viewed ventrally the inner processes of the catapophyses are 
seen to have united to form a subcentral arch which hides between a quarter and a third 
of the ventral surface of the centrum. The preaxial margin of this arch exhibits a 
median notch with a convexity external to it on each side. Postaxially its margin is 
deeply concave. Its ventral surface exhibits a blunt, median, antero-posteriorly ex- 
tending prominence with a concavity on each side of it, which concavity is serially 
homologous with the little antero-posteriorly extending groove on the ventral surface 
of the catapophysis of the seventh vertebra. 
The lateral catapophysial margins of the median subcentral groove on the ventral 
surface of the centrum are still sharper and more prominent than in the seventh 
vertebra, so that the groove is somewhat deepened, and it is the dorsal part of the wall 
ot this groove which is perforated just behind the catapophysial (or hypapophysial) 
bridge by the oval foramen just mentioned. 
