197 
so constant and well-marked, that the Comparative Osteologist, who had had the oppor- 
tunity of comparing them, would afterwards readily distinguish the genera Struthio, 
Rhea, Casuarius and Dromaius, by the sternum alone. That bone in the Apteryz is still 
more characteristic of the genus, and it is to this particular modification of the keel-less 
sternum that the sternum of one or both genera of the gigantic wingless birds of New 
Zealand makes the nearest approach. This is exemplified in the attempted restoration 
of the sternum of a large species' referred to Dinornis prior to the reception of the evi- 
dence afforded by the cranium and beak of two genera of large wingless birds in New 
Zealand. ‘That sternum may, however, belong to the Palapteryx robustus: it was ob- 
tained, it will be remembered, from the same deposit at Waikawaite in the Middle 
Island, from which the most abundant and instructive evidences of that species have 
been had. The restoration was unavoidably imperfect, as regards especially the form 
and extent of the anterior or costal angles (a, Pl. XXXV.), but was sufficiently esta- 
blished to illustrate the nearer resemblance of the sternum in form to that of the 
Apteryx than to that of any of the larger existing Struthious birds. 
A much more perfect specimen of the sternum (Pl, XLYIII. figs. 1-4) of a smaller 
species of the great wingless birds of New Zealand confirms the general accuracy of the 
restoration attempted in the Memoir on the Palapteryx (p. 124), and affords additional 
illustration of a near affinity to the Apterya, For this reason I refer the sternum in 
question to the genus Palapterye. Like that of the Apteryx, this sternum is remarkable 
for its shortness in comparison with its breadth, and for the breadth and depth of the 
two posterior notches. The chief difference is presented by the anterior border, which 
extends in almost a straight line from one costal angle to the other. These angles are 
produced into short, broad, subcompressed processes, rounded and thick at their free 
and expanded ends, and slightly twisted upon their neck, or point of attachment. Only 
three articular surfaces for sternal ribs are indicated (fig. 3), the intervening fossz 
being very shallow; and the whole extent of the costal border is shorter than in the 
Apteryx, and resembles in this respect that in the Galline, Pigeons, and Penguins. The 
coracoid fosse are small and unusually shallow ; there is a large depression on each 
side of the fore part of the concave surface of the sternum nearly opposite the coracoid 
fossze, the bottom of which is cribriform ; numerous small foramina having apparently 
conducted air from the anterior thoracic cells into the sternum. That bone in the 
Apteryx shows no trace of such depressions. The bone, which is cellular at the thicker 
parts of the periphery, is very thin and compact at the middle of the body of the 
sternum. 
The posterior border is marked by two deep and wide angular emarginations leaving 
a broad middle process with two very long and narrow diverging lateral ones ; but the 
extremities of all these processes have been broken away. ‘The chief specific distinction 
of the sternum in question, which is that of a mature bird, from the sternum figured in 
Vide supra p. 124. Pl. XXXYV. figs. 1, 2 & 3. 
