32 Philippine Journal of Science ms 
Academy of Natural Sciences of Philadelphia, but was unable 
to do so. 
It is very much to be regretted that a skull of the harpy eagle 
is not at hand for comparison with that part of the skeleton of 
Pithecophaga. Probably there is not a cleaned skull of the harpy 
eagle in the United States — adult, subadult, or young. This is 
invariably the case with respect to any bird before a glut takes 
place in museums and private collections of birds ; the skulls are 
left in the skins! 
THE CRANIUM, MANDIBLE, AND ASSOCIATED BONES OF PITHECOPHAGA 
It matters but little from what point of view we may regard 
the cranium of this great eagle, the fact will at once be ap- 
preciated that at least two of its characters are so pronounced 
and so characteristic of the species that to confuse this part of 
the skeleton with the cranium of any other known eagle would 
be quite out of the question. In the first place, the lacrymal 
bones and their accessory outer pieces are of great size, while a 
still more conspicuous character is to be seen in the size and 
form of the osseous superior mandible ; this is powerfully hooked, 
with cuitrate tomia. It is transversely compressed almost to the 
last degree, the transverse diameter at the base beneath being 
slightly less than 2.5 centimeters, while the vertical height at 
the same point measures nearly 4 centimeters. Measured me- 
sially below, it has a length of about 5.02 centimeters. Either 
narial aperture is very large, and these openings do not com- 
municate through and through ; anteriorly either one merges into 
the general surface of the side of the beak, while posteriorly 
greater depth is present, and the surrounding margin is sharp 
and triangular in outline; the apex of the triangle is posterior 
and above (Plate I, fig. 1). 
Turning to the large lacrymals mentioned above, their form 
and proportions are well shown in the illustration (Plate I, fig. 
2), while the descending limb is portrayed on the same plate. 
As is the case with so many large raptorial birds, these lacrymal 
bones, in adult life, do not fuse with the frontal and nasal upon 
either side nor with the large, subtriangular accessory piece 
supported at the outer end of each (fig. 2). The descending 
orbital limb of a lacrymal is constricted superiorly, anteropos- 
teriorly flattened below, while it is broader and concaved in front 
from above downward. This part of a lacrymal does not come 
in contact either with the small, thin pars plana within or 
with the zygoma below. 
