358 PROF. ST. GEORGE MIVART ON THE 
the tenth, and is like it except that the prazygapophyses again extend a little less 
dorsad (as they have begun to do in the tenth vertebra), while from behind the summit 
of each a sharp, pointed, metapophysial process extends dorsad, postaxiad, and externad. 
The hyperapophyses are more developed (especially elongated); and there is no longer 
any trace of a neural spine. ; 
The median ventral ridge of the hemal arch has here become a very sharp, plate-like, 
prominent process. 
The TWELFTH VERTEBRA (Plate LVITI. fig. 33) is of about the same length as the 
eleventh, and is like it except that the hind ventral process of the hemal arch is more 
prominent, the hyperapophyses are larger, and the postzygapophyses here again begin 
to fail to extend postaxiad so far as does the centrum. 
The THIRTEENTH VERTEBRA is slightly shorter than the twelfth, and repeats its cha- 
racters a little more strongly marked, except that the hemal arch projects preaxially 
to the centrum in a somewhat less degree. The hyperapophyses project sharply and 
strongly dorsad and preaxiad. 
The FOURTEENTH VERTEBRA is again a little shorter. The postzygapophyses begin to 
project postaxiad slightly beyond their articular surfaces. It has no longer the pointed 
process just postaxial to the preezygapophysis, or only a rudiment of such. Long cata- 
pophysial ridges limit laterally the subcentral groove, though they altogether disappear 
in the next vertebra. 
The FIFTEENTH VERTEBRA (Plate LVIII. figs. 34-36) is of about the same length as the 
fourteenth. It is like it; but the rib-like styloid processes are stouter, more externally 
placed, and are more decidedly parapophysial. The hemal canal has ceased to exist; 
and in its place is a long plate-like hypapophysis, which may be perforated. 
The hyperapophyses converge preaxiad, and may meet to indicate a rudiment of a 
neural spine’. The postzygapophyses begin again to project postaxiad a little beyond 
the centrum. 
The SIXTEENTH VERTEBRA is of about the same size as its serial predecessor, but differs 
from it markedly in the sudden development of a long neural spine, curved postaxiad 
at its tip. There is also a still larger plate-like hypapophysis, projecting postaxiad of 
the centrum, and considerably larger than in the corresponding vertebra of Phala 
crocoraxz. The prezygapophyses begin again to extend preaxiad as much as does the 
centrum. ‘The rib-like styloid processes are shorter and stouter, and notched preaxially, 
while the lamella, enclosing dorsally the lateral vertebral canal, extends more postaxiad, 
and is therefore longer antero-posteriorly than in the fifteenth vertebra. 
The SEVENTEENTH VERTEBRA is of about the same size as the sixteenth; but its neural 
* This vertebra, in the specimen of P. nove-hollandic in the Royal College of Surgeons’ Museum, has a neural 
spine more developed than has even the sixteenth vertebra of P. anhinga (in either specimen), while its four- 
teenth vertebra is quite like the fourteenth vertebra of P. anhinga. This, coupled with the defective number 
of cervical vertebra, makes it probable that the fifteenth is lost in this specimen. 
