428 



ME. ST. GEOEGE BIIVAET ON THE 



THE CAUDAL VERTEBEtE. 



The Forty-seventh Vertebra. 

 This vertebra remains normally unanchylosed with the preceding bone in the adult 

 bird. 



It has a massive centrum and a neural arch small in circuit and very little develoj^ed 

 antero-posteriorly, with a wide and massive neural spine and a moderate transverse 

 process. 



The centrum has its postarial surface nearly flat or slightly concave or convex. 

 Its dorsal margin is slightly concave, its ventral margin very slightly convex. 

 The preaxial surface of its centrum is slightly concave, and its ventral margin nearly 

 straight. 



THE FORTY-SEVENTH, ok FIRST CAUDAL VERTEBRA (natural size). 

 Fis. fi3. . Fig. 64. 



Fig. 63, prea.xial aspect ; 64, lateral aspect (left side). Letters as before. 



The ventral surface of the centrum shows the subparallel antero-posterior excavations 

 separated by a considerable interval. The excavations, however, are less extensive than 

 are those in more preaxial vertebrse. 



The diapopkysis (figs. 63 & 64, d) projects dorsad, outwards and very slightly post- 

 axiad ; it is subcorneal, rather flattened pre- and postaxially, and with a somewhat 

 rounded extremity. A very small parapophydal process projects from or ventrad of 

 the ventral side of its root, extending slightly outwards from the lateral margin of the 

 ventral surface of the centrum at or postaxiad of the antero-posterior middle point of 

 that margin (figs. 63 & 64, ^j). 



The neural lamina of each side has its postaxial margin nearly vertical ; but its pre- 

 axial margin is inclined preaxiad and dorsad. 



The neural spine is much more developed transversely than antero-posteriorly, and 

 shows a tendency to bifurcate, its lateral extremities extending more or less outwards 

 and preaxially. 



There are no zygapophyses. 



