PROFESSOR OWEN ON THE GENUS DINORNIS. 117 
depressions and foramina, their sternum receiving air exclusively from the intercostal 
fossee, whilst these in Dinornis are imperforate (Pl. VII. fig. 2, 0 0 0). 
The anterior border of the sternum of D. rheides (Pl. IX. fig. 4) is straight, no part 
projecting forward as “‘manubrium” or receding; it is slightly and equably curved trans- 
versely toward the chest (as shown at a, fig. 4); it is strongly bent from without inward, 
or from below upward, where it terminates by a narrow subobtuse margin, overhanging, 
in the vertical position of the bone, the pneumatic depressions and the general concavity 
of the inner surface. This margin is continued on into each costal process (figs. 3 & 4, 
d d), which extends upward and outward in the same slight transverse curve for rather 
more than an inch beyond the costal border, with an antero-posterior thickness, at the 
middle, of 9 lines, and with an obtuse and apparently slightly expanded termination, 
which, however, is not quite entire in the specimen. 
The coracoid depressions (fig. 4,40) are feebly defined by a transverse concavity 
occupying the fore part of the costal process, not extending mesially much beyond the 
line of the outer or lower border of the costal tract (fig. 4,¢¢). This tract (Pl. VIII. 
fig. 2) shows ridges for the articulation of two sternal ribs, the anterior one (i) being 
bituberculate, as in the Ostrich; the posterior and shorter ridge (n) is simple: three 
intercostal fossee (000) are defined by these ridges; the anterior and largest has a 
somewhat irregular surface, the two following are smoothly concave. 
The sternum, which is 1 inch across the first fossa, contracts to a thickness of 4 lines 
at the end of the third fossa. The length of the costal tract is 2} inches. The outer 
border of the lateral process (4) continues obtuse but decreasing in thickness to about 
one-third from the lower end, where it becomes a ridge: the inner border is a sharper 
ridge through the whole extent. The length of each lateral process is 6 inches, the 
average breadth 6 lines, being very little more at its commencement. 
The length of the sternum in a straight line along the middle is 9 inches: the lateral 
processes (4h) extend about an inch beyond the middle one (g); this, halfway from 
its commencement, measures 2 inches across. 
The breadth of the sternum at the ends of the lateral notches (ff), or origins of the 
lateral processes, is 5 inches 6 lines; the breadth of its fore part, including the costal 
processes (d d), in a straight line is 7 inches. 
The middle of the entire part of the sternum is reduced to the thinness of cartridge- 
paper; it gains a little in thickness at the median process; but this thins off again to 
the end. 
The outer surface is marked by fine lines, indicative of aponeurotic insertions; the 
inner surface is for the most part smooth and polished. 
Longitudinally both median and lateral processes have a slight outward or downward 
flexure, giving a gentle sigmoid contour to the bone in that direction, as in fig. 2, 
Pl. VII. 
The second sternum of Dinornis rheides in the collection examined at Mr. Sumpter’s 
R2 
