822 PEOF. ST. GEORGE MIVAET ON THE 



axiad but dorsad, and fail to project preaxially as much as does the centrum. The 

 articular surface of each prsezygapophysis 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 (i. 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 metaj)0]}l)ysis [m) appears as a slight prominence outside the preezj'gapophysis. 



Seen dorsal/// (fig. 14), a marked fossa is visible on each side postasial to (and as it 

 were continued on from) the prtezygapophysis. These fossse receive the postz)'gapophyses 

 of the seventh vertebra when it is much bent back upon the eighth vertebra. The 

 hyperapopliyses, 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 fonvards 

 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 mntrally 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 

 of this groove which is perforated just behind the catapophysial (or hypapophysial) 

 bridge by the oval foramen just mentioned. 



