360 PEOF. ST. GEORGE MIVAET ON THE 



This vertebra, liowever, agrees with the corresponding one of Phalacrocorax in that 

 in it the prsezygapophyses again, for the first time, do not extend so far preaxiad as the 

 preaxial end of the centrum. 



The Dorsal Vertebrae. 



These vertebrae (Plate LVIII. fig. 46) agree with the dorsal vertebrae of Phalacro- 

 corax in being laterally compressed and strongly hypapophysial, or rather catapophysial, 

 since the hypapophyses are differently formed, i. e. from medianly coalescing lateral 

 hypapophyses. 



The TWENTY-FIRST VERTEBRA differs from the twentieth in that the median hyj)apo- 

 physis has all but disappeared (being only a rudimentary median ridge), while the lateral 

 hypapophyses, though reaching to the postaxial end of the centrum on each side as 

 lateral ridges, yet have their long, outstanding, distally depressed processes confined to 

 a rather smaller extent of the preaxial part of the centrum. The preaxial surface of the 

 centrum is less concave, its postaxial surface more so. 



Compared with the same vertebra in Phalacrocorax, the preaxial articular surface of 

 the centrum is more quadrangular, the centrum is less compressed laterally and more 

 ventrally flattened. The median hypapophysis has disappeared ; but there are con- 

 spicuous lateral hypapophyses. The transverse processes project less outward, but are 

 more antero-posteriorly developed. The fossa beneath the root of the transverse process, 

 which is so conspicuous in Phalacrocorax, is here wanting. 



The TWEKTY-SECOND VERTEBRA (Plate LVIII. fig. 44) differs from the twenty-first mainly 

 on its ventral aspect. Its centrum is much more laterally compressed ; and the median 

 hypapophysis has quite disappeared ; the lateral hypapophyses (already in the last 

 vertebra slightly more ventrad than in the twentieth vertebra) have coalesced medianly 

 under the postaxial half or more of the centrum, while their preaxial ends project out- 

 wards, downwards, and backwards, but are much smaller than in the twenty-first ver- 

 tebra. This vertebra is also more decidedly opisthocoelous than its serial predecessor. 



Compared with the same vertebra of Phalacrocorax, the centrum is slightly more 

 preaxially convex (especially dorso-ventrally) and postaxially concave. The transverse 

 processes differ much as do those of the twenty-first vertebra. There is no true median 

 hypapophysis ; but, as has been said, the lateral hypapophyses bend down and unite to 

 form postaxially a coalesced, vertical, hypapophysial lamellar process. 



The TWENTY-THIRD VERTEBRA (Plate LVIII. fig. 45 & Plate LXI. figs. 6, 7, 8, xxiii) differs 

 from its predecessor mainly in that its centrum is still more laterally compressed, and 

 that the lateral hypapophyses have still more completely united medianly, there being 

 now only two small diverging processes at the preaxial end of a median, vertical, sub- 

 central plate, the ventral outline of which is concave antero-posteriorly. 



Compared with the same vertebra of P/ia/acrocoraiT, its centrum is even more laterally 

 compressed ; the hypapophysis is also shorter, and, as has been said, its distal preaxial 

 end bifurcates. 



