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. 



Vent rally, 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 vertebrse 

 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 trabecular are 

 thrown up into the deep space above. Finally, the two terminal 

 sacral vertebras occupy a much lower plane than the preceding — 

 that is, their transverse processes do — and these are thrown 

 directly outward, to fuse distally with the inner wall 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 vertebrse 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- 

 bular; 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. 



