410 MR. ST. GEORGE MIVART ON THE 
The postazxial aspect of the centrum shows an articular surface which may be more 
quadrate, its ventral margin often less preponderating over its dorsal margin than in 
the preceding vertebra. The latter is also less concave, while the former is nearly 
straight and may even be very slightly convex. 
The yentral surface has its preaxial margin more expanded and less sharply concave, 
and its postaxial margin often less convex than is the case with the eighteenth vertebra. 
The hypapophysis is a single rounded, obtuse tubercle. It extends rather more 
ventrad and sometimes less preaxiad than does that of the preceding vertebra. The 
under surface of the centrum may be concave antero-posteriorly in the middle line 
behind the hypapophysis. 
NINETEENTH VERTEBRA (3 natural size). 
Fig. 43. 
Aspects. 
Fig. 42, lateral; 48, preaxial; 44, dorsal. Letters as before. 
The ventral aspect of the hypapophysis exhibits, as it were, a slight lingering 
tendency to bifurcate. 
Behind the hypapophysis the surface of the centrum begins to be slightly convex 
transversely instead of being concave. 
Not only is there, as has been said, no pleurapophysial band of bone, but no ridge 
runs postaxially from the parapophysis, the side of the centrum being continued unin- 
terruptedly dorsad into the side of the neural arch, the whole forming one concayo- 
convex expanse. 
The parapophysis extends preaxially and slightly outwards, and has at the outside of 
it a small, rather deep, concavity for the head of the rib, and on its inner side the lateral 
continuation of the preaxial central articular surface (fig. 42, p). 
The diapophysis projects slightly more outwards from the prezygapophysis, is more 
antero-posteriorly extended; and the dorso-ventral distance between it and the parapo- 
physis is greater than heretofore, extending to the preaxial margin of the neural 
lamina. From its ventral outer side, near its preaxial end, the diapophysis develops a 
rounded prominence (fig. 42, d) to receive the tubercle of the rib. Beneath it the 
preaxial surface of the neural lamina is deeply and irregularly excavated, and another 
