52 Philippine Journal of Science 1919 



of the companion bone of the leg. Below this, it runs onto the 

 shaft, and here the contact almost amounts to a direct fusion 

 with it. At its lowest point it is not over 3.5 centimeters above 

 the lower margin of the external tibial condyle. All diurnal 

 Raptores possess fibulae of greater or less length; especially do 

 we find this to be the case in Pandion. Superiorly, in our sub- 

 ject, the fibula is much compressed, from side to side, with its 

 head produced posteriorly. Its entire summit/ convex from be- 

 fore backward, is an articular facet for the outer condyle of the 

 femur. 



Pithecophaga possesses a rather large patella, which is elon- 

 gate from side to side, in which direction the surface is convex, 

 while posteriorly it is concave above and doubly concave poste- 

 riorly for articulation with the condyles of the femur. Inf eriorly, 

 the surface is limited and flat. Sometimes, as in the case of our 

 present subject, there is a small, circular ossification in the 

 tendon of the muscle, several millimeters below the true sesamoid 

 of the knee joint ; it occurs in both limbs. 



Eagles exhibit very considerable variation in their leg bones, 

 but more in the tibiotarsus than in the fibula. For instance, in 

 the harpy the latter bone is more than a centimeter shorter than 

 it is in the Philippine bird now being described, while at the 

 same time the shaft is very conspicuously flattened from before 

 backward ; at the same time, this flattening is associated with a 

 marked increase in the shaft's width. With respect to the fibula 

 of the harpy, it broadens below the articular ridge, and is grooved 

 for the passage of the muscle that passes over it (Plate VII, 

 fig. 1). In the white-headed eagle the cnemial processes of the 

 tibiotarsus are greatly reduced in all particulars, and to a lesser 

 extent this is also true of the Korean eagle ; the fibula is very 

 long in the species. 



With respect to the golden eagle (Aquila chrysaetos canaden- 

 sis), the bones of the leg are nonpneumatic for their entire length 

 below the proximal extremities, the shaft of the tibiotarsus in 

 this species being curved from end to end, the concavity being 

 along the inner or mesial aspect. 



Skeleton of the foot. — Plates X and XI. As already noted, 

 the tarsometatarsus and other bones of the foot in this eagle 

 are entirely nonpneumatic, while in some other forms the re- 

 verse of this is the case (Haliseetus leucocephalus) . Irrespective 

 of species the tarsometatarsus possesses the same general char- 

 acters throughout the group, and its form is very characteristic. 

 All this part of the skeleton in the harpy was left in the skin of 



