42 
Philippine Journal of Science 
1919 
The pubic style closes the obturator foramen; and, after pass- 
ing it along the lower margin of the ischium, it becomes much 
attenuated and terminates as a fine point in a line below the 
middle of the ischiadic foramen above it. A small interval is 
then present, when the bone begins again in a fine point, to 
increase gradually in size as it passes below the inferior ischiac 
border, to be produced posteriorly in 'a much thickened condition 
in the direction of its fellow of the opposite side. 
Ventrally, the pelvis of this eagle presents many interesting 
features. As well as I am able to judge from the pelvis of an 
adult bird of this species, the sacrum would seem to contain 
fifteen vertebrse, or the same number as we find within the 
grasp of the iliac bones of the harpy’s pelvis. The leading 
seven possess very large centra, and they have their lateral pro- 
cesses extending upward and outward, to coossify with the 
ventral surfaces of the ilia. Posterior to this arrangement, we 
arrive at the very deep pelvic basin, where the three vertebrae 
opposite the cotyloid rings fail to throw out lateral processes. 
These are followed by three others that have the lateral processes 
for their external moieties fused into a common plate of bone 
upon either side, which fuses outwardly with the inner surface 
of the pelvic wall. A row of three elliptical foramina is left 
upon either side of the centra here, and osseous trabeculae are 
thrown up into the deep space above. Finally, the two terminal 
sacral vertebrae occupy a much lower plane than the preceding — 
that is, their transverse processes do — and these are thrown 
directly outward, to fuse distaily with the inner wail of the 
ischium upon either side. Below them the surface — and it is 
an extensive one — on either hand is smooth, being furnished 
entirely by an ischium. 
The conformation I have attempted to describe here gives 
rise to four fairly well-defined cavities, each imperfectly walled 
in by the surrounding parts of the pelvis as a whole. Through 
these cavities, mesially, passes the big, coosified pelvic “sacrum.” 
The first cavity occupies the anterior half of the pelvis back- 
ward to a point where the vertebrae cease to send their lateral 
processes directly outward to the iliac walls upon either hand. 
Then follows the well-marked, deep cavity opposite the aceta- 
bulae; posterior to this we define cavity number three, which 
lies between the big ischiadic foramina; and, finally, ventrad to 
the last two, there is the general concavity of the pelvic basin, 
having cavities two and three above it, and its lateral walls 
formed by the ischium, descending deeply upon either side. 
