338 PEOF. ST. GEORGE MIVAET ON THE 



The interzygapophysial ridge is very much more prominent; and the outline of the 

 upper border of the neural arch is strongly concave. The prsezygapophyses look more 

 dorsad. There is a prominence outside the root of the rib-like styloid process (which 

 latter is much longer relatively than in Pelecanus), separated from the rudimentary 

 metapophysis (m) above it by an antero-posterior groove (Plate LVI. fig. 4). 



The FOURTH VERTEBRA repeats the general characters of the third ; but the rib-like 

 process is longer, the metapophysis stronger, and the hypapophysis smaller (though 

 still large), with only a single groove on its ventral surface. 



The FIFTH VERTEBRA is like the fourth, but that the still plainly parapophysial rib-like 

 process is slightly longer, and the metapophysis larger, with no groove on its ventral 

 side (Plate LVI. fig. 5). 



The hypapophysis has become replaced by a more or less narrow median subcentral 

 groove, from the sides of the wide, more preaxial, part of which minute prominences 

 indicate the commencement of catapophyses or lateral hypapophyses (c). 



The SIXTH VERTEBRA (Plate LVI. figs. 6-8) is rather longer, has the hyperapophyses 

 much more developed, the metapophyses more marked, and the subcentral groove wider. 

 The underpart of centrum is very convex antero-posteriorly, the vertebra being, as it 

 were, flexed dorsad at each end towards its ventral surface. The catapophyses are more 

 marked than in the fifth vertebra ; and the diverging rib-like styloid processes are still 

 plainly parapophysial. The vacant space between these processes and the catapophysial 

 ridges of the centrum corresponds with the groove between the catapophysis and the 

 parapophysis on each side of the centrum of the sixth vertebra of Pelecanus. 



The SEVENTH VERTEBRA presents similar differences to its predecessor from the seventh 

 of Pelecanus, except that the postzygapophyses do not project more postaxiad, nor 

 is the postaxial margin of the neural arch more concave. The hyperapophyses are 

 advanced as in Pelecanus, but they generally form ridges diverging postaxiad from the 

 summit of the neural spine. The styloid parapophysial processes and catapophyses 

 are essentially similar to those of the sixth vertebra, but they are somewhat more 

 approximated (Plate LVI. figs. 9-12). 



The EIGHTH VERTEBRA in Sula (Plate LVI. figs. 13-17) contrasts with its predecessor 

 even more than it does in Pelecanus, except that the neural arch is not cut away so much 

 more preaxially, that there is not so much difference as to the preaxial opening of the 

 lateral canal, nor in the shape and direction of the postaxial surface of centrum. The 

 hyperapophyses also are less marked; and the catapophyses do not form a haemal arch. 

 On the other hand, the metapophyses are suddenly very much developed, presenting a 

 rugged outstanding process, irregularly flattened behind, projecting dorsad and externad 

 from the dorsal part of the outside of the pleurapophysial lamella, just external to the 

 praezygapophysis. 



The rib-like styloid processes are more slender, and closely approximated to the 

 Small catapophyses ; and they have become so much more ventral and median in posi. 



