PROFESSOR OWEN ON THE GENUS DINORNIS. 17 
Zealand. That sternum may, however, belong to the Palapteryz 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. 43, vol. ill.), but was sufficiently 
established 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 (PI. IV. figs. 1-4) of a smaller species 
of the great wingless birds of New Zealand confirms the general accuracy of the restora- 
tion attempted in my Memoir of 1846, and affords additional illustration of a near affinity 
to the Apteryz. For this reason I refer the sternum in question to the genus Palapteryz. 
Like that of the Apteryz, 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 (a, a) 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 ster- 
nal ribs are indicated (fig. 3), the intervening fosse 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 fossz (c,c) are small and 
unusually shallow ; there is a large depression on each side of the fore part of the con- 
cave surface of the sternum nearly opposite the coracoid fossz, 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 Apterya shows no trace of such de- 
pressions. 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 
vol. iii. pl. 43, is its smaller size, and the angular form of the posterior notch, which was 
rounded at the bottom in the larger sternum, as in the Apterya. 
A distinct form of sternum, although evidently appertaining to a bird which was de- 
prived of the power of flight, is that which is represented in Pl. IV. figs. 5-8. The 
specimen is part of the collection obtained by Mr. W. Mantell at Waingongoro, and 
which was sold by Dr. Mantell to the British Museum ; where, for the facilities afforded 
for describing and figuring the specimen, I feel indebted to the kindness and urbanity 
of the learned Keeper of the Department, Charles Kénig, K.H., and of his able Assistant 
Mr. Waterhouse. 
Its proportions would justify its reference to a bird of the size of that to which the 
VOL, IV.— PART I. D 
