360 PROF. ST. GEORGE MIVART ON THE 
This vertebra, liowever, agrees with the corresponding one of Phalacrocorax in that 
in it the prezygapophyses again, for the first time, do not extend so far preaxiad as the 
preaxial end of the centrum. 
Tae Dorsat VERTEBRE. 
These vertebre (Plate LVIII. fig. 46) agree with the dorsal vertebrae of Phalacro- 
coraaz in being laterally compressed and strongly hypapophysial, or rather catapophysial, 
since the hypapophyses are differently formed, ¢.e. from medianly coalescing lateral 
hypapophyses. 
The TWENTY-FIRST VERTEBRA differs from the twentieth in that the median hypapo- 
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 Phalacrocoraa, 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 TWENTY-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 opisthoccelous than its serial predecessor. 
Compared with the same vertebra of Phalacrocoraz, 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, x11) 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 Phalacrocoraz, its centrum is even more laterally 
compressed ; the hypapophysis is also shorter, and, as has been said, its distal preaxial 
end bifurcates. 
