406 MR. ST. GEORGE MIVART ON THE 
As regards the centrum, its preaxial surface has the shape of its ventral margin 
changed by the appearance of two small hypapophysial processes (fig. 36, hy). 
Its postaxial surface is larger both actually and relatively; while its ventral margin 
has once more become more extended transversely than its dorsal margin, and at the 
same time is less concave than in the vertebra last described (fig. 37, pc). 
The neural surface of the centrum may be more exposed by the further cutting 
away, as it were, of the preaxial part of the neural arch. 
The ventral surface of the centrum presents somewhat of a return to the proportions 
of the third vertebra, if abstraction is made of the hypapophyses (fig. 39). 
SEVENTEENTH VERTEBRA (3 natural size). 
Aspects. 
Fig. 35, lateral ; 36, preaxial; 37, postaxial; 38, dorsal; and 39, ventral. Letters as before, 
These latter processes (which may conveniently be said to represent and take the 
place of absent catapophyses) project as a pair of short processes, springing from 
beneath about the middle (both antero-posteriorly and transversely) of the centrum. 
They extend ventrally and preaxially, and diverge from each other towards their apices, 
instead of converging like the catapophyses of the sixteenth vertebra. 
The hypapophyses may be separated by a notch which extends dorsad to the general 
level of the ventral surface of the centrum, or may be only imperfectly divided from one 
another as in the specimen figured. 
