586 Transact} cms of the Royat Society of Sotith Africa. 
say, in passing, that the scapula, o£ this macaw is remarkably short and 
considerably expanded at its distal extremity, and the upper parts of the 
clavicular heads are pneumatic, with the foramina in plain view at either 
posterior apex of the bone. Indeed, in these large parrots all the bones of 
the pectoral arch or shoulder-girdle are more or less pneumatic, as is nearly 
all the rest of the skeleton. 
Although it does not show as much as I should like, still a fair idea of 
the form of the sternum in Palaeornis may be gained from Figs. 6 and 8 on 
Plates XL and XLI of this paper. It presents all the average characters of 
this bone in the parrots generally, and I have compared it with that bone as 
it occurs in quite a number of species and genera. Considerable depth and 
marked thinness are two of the principal features seen in the carina or keel 
of the bone, which is so extensive that it not only springs from the entire 
length of the body of the sternum beneath, but projects anteriorly to a large 
extent, and it is here that its greatest depth is seen. On either side there 
is a raised welt descending directly downward from the coracoidal groove to 
the raised pectoral muscular line, which, as usual, runs forwards and back- 
wards on the side of the keel. The carinal angle is broadly rounded off, 
constituting a striking feature in the sterni of all parrots. A conspicuous 
mamihrial process projects almost directly upwards ; it has a flat, triangular 
surface in front, and is fashioned posteriorly to form a part of the articular 
area for the coracoids. The groove for the accommodation of these bones is 
deep and narrow, the articular sui-face in them being continuous. 
As in most Psittaci, the coracoidal processes are greatly reduced, being 
mei'e low, triangular elevations of no great proportions. Back of them, on 
either side, we find the six transverse facets for the costal ribs. The body 
of the sternum of this parrot is shortish as compared with its width, and 
notably more so as compared with the shape of the body of the bone in the 
macaws (Ara). Superiorly, it is deeply concave and correspondingly con- 
vex on its ventral aspect. Its xiphoidal or posterior margin is the widest 
part of the bone, being very slightly convex outwardly ; thin, notwith- 
standing that it is defined by a perceptible thickened edge on its ventral 
side, and withal entire — that is, never presenting any "notching" what- 
ever. 
On either side of the carina, and well within this posterior border, there 
is to be found a subcircular foramen of some considerable size. Along the 
anterior three-fourths of the line of the keel or median line, on the dorsal 
aspect of the sternum, are to be noted numerous pneumatic foramina, and 
similar air-sac apertures of no great size pass from the anterior termination 
of this median row, along the side of the bone, as far back as points opposite 
the last articulations of the ultimate pair of costal ribs. 
All the big macaws (Ara) have the xiphoidal foramina comparatively 
}nucli larger than we find them in Palaeornis, and the pneumatic foramina 
