Parker.—On Notornis mantelli. 258 
of any importance to this rule are in respect of the length of the scapula 
and of the sternum, both of which are proportionally longer in Notornis 
than in Tribonyx, instead of shorter, as they would be if the rule held good 
throughout. As regards the sternum and shoulder-girdle, Notornis is 
intermediate between Porphyrio—or rather Tribonya—and Ocydromus, but in 
the character of the pelvis it differs far more from the normal ralline type 
than does Ocydromus. 
It has always been acknowledged that Notornis is a degenerate rail, its 
special and aberrant characteristics being due to structural modification con- 
nected with the disuse of the wings and the assumption of purely cursorial 
habits. And I think it is impossible to avoid the conclusion that we have in 
Porphyrio the nearest living representative of the typical ralline ancestor of 
Notornis, and in Tribonyx the nearest living representative of an important 
intermediate stage in the process of degeneration. 
The degenerate character of Ocydromus is equally evident, but this genus 
must be looked upon as descended from a strictly ralline, not from a porphy- 
rionine ancestor; in other words, as having come along an entirely 
different line of descent from Notornis, with which it must have, therefore, 
_ only a collateral relationship. : 
Tregret that the absence of specimens in this Museum prevents my 
instituting a comparison with Aptornis, but judging from Professor Owen’s 
_ figures, it seems to me that this largest of rails is a further development, by 
: degeneration, of an ocydromine type. For instance, the short sternum, 
_ “harrowing posteriorly, seems a sort of exaggeration of that of Ocydromus, 
_ and the pelvis approaches in its proportions to the same genus, having a far 
__ less proportional breadth than in Notornis. . 
| These conclusions are expressed in the following diagram :— 
Aptornis. 
Notornis. goers 
