PHYLOGENY OF THE PALZOGNATHEA AND NEOGNATH®. 221 
this region of the sternal plate is much thickened to form a prominent lip, looking 
upwards. ‘The coracoid grooves are exceedingly shallow and only just visible. As in 
Apteryx, these grooves lie far apart, at the antero-lateral angle of the sternal plate. 
The anterior lateral processes are short; the articular surfaces for the sternal ribs lie 
crowded together immediately behind the anterior lateral process, as in Rhea. The 
posterior lateral processes are of great length; the metasternum is often of great 
length. The form of this and of the posterior lateral processes varies much in the 
different groups into which the Dinornithes are divided. The length of the meta- 
sternum in Apterya does not extend beyond the posterior lateral processes. 
In Epyornis the sternum resembles that of Apterya more nearly than any other 
Palwognathe. As in Apteryx, the anterior border of the sternal plate is deeply 
notched, the coracoid grooves are widely separated and very similar in form. ‘The rib- 
facets are wide and well spaced along the lateral border as in Apterya, not crowded 
together as in Rhea or Dinornis. There are short but well-marked posterior lateral 
processes, but there is no metasternal element. As Andrews has pointed out in a 
recent and admirable paper on the skeleton of this bird, the sternum of Apyornis 
represents an embryonic stage. 
As Mr. Andrews has pointed out [4], the ‘sternum of 4pyornis consists of the two 
primitive costo-sternal elements only, and in this respect corresponds to an embryonic 
stage in the development of the sternum in the recent Ratite.” More especially does 
this seem to apply, he goes on to point out, to the embryonic sternum of Apteryz. 
The sternum of the Crypturi differs from that of the flightless Palwognathe 
chiefly in the possession of a large keel. In general form the corpus sterni recalls that 
of Anomalopteryx. This is chiefly due to the large posterior lateral processes, which 
in Crypturi arise very far forwards. ‘The articular surfaces for the sternal ribs are 
closely crowded and lie on either side of the coracoid grooves. The interarticular 
spaces—incisure intercostales—form deep pocket-like apertures, as in Dinornis and Rhea, 
for instance. The crowding together and forward position of the articular surfaces for 
the sternal ribs is another Rheine character. 
The anterior lateral processes are very similar in form and position to those of Rhea, 
which they still further resemble in that the ventral aspect of the base lodges a 
pneumatic aperture. 
The coracoid grooves in the Crypturi are separated by a deep gorge carved out of 
the corpus sterni. ‘These grooves differ from those of Rhea in that the upper and lower 
lips are better developed, and in that their transverse extension is less while their depth 
is greater relatively. 
There is a large spina interna. 
Turning once again to the corpus sterni and comparing that of Rhea macrorhyncha. 
kindly lent me by Mr. Beddard, with that of a Timamon, we notice a point of some 
significance. To wit, that in Rhea on either side of the great median protuberautia 
vou, Xv.— Part v. No. 15.— December, 1900. 21 
