38 
Philippine Journal of Science 
1919 
them, the lower end of the tube not having more than half the 
caliber of the upper, where it makes a simple union with the 
larynx. Distally, the bronchial branches are small, and but 
half closed in, the mesial aspect of either being a thin, simple 
membrane stretched across. There is a single pessalus present. 
THE SKELETON OF THE TRUNK 
The vertebral column. — All the skeletons of eagles that I have 
examined possess fourteen vertebrae in the cervical region of 
the spine, between the cranium and the first true dorsal vertebra. 
Each of the last two cervicals — the thirteen and the fourteenth 
— supports a free pair of ribs. On the thirteenth the pair is 
rudimentary, to the extent that the body of the bone on either 
side is lacking to some considerable degree, while the articulation 
is perfect for the head and angle. With respect to the pair 
of ribs on the fourteenth cervical vertebra, it has a length 
of some 5 centimeters, terminating in a pointed, free extremity 
well above the sternum. As this is the case with respect to 
these last two vertebra; in Pithecophaga, Thrasaetos harpyja, 
Aquila, and our white-headed eagle, it is probably what we will 
find in the skeleton of any true aquiline species, irrespective 
of the part of the world it inhabits. As a matter of fact, the 
vertebral column of this monkey-eating eagle of the Philippines 
is, character for character, almost the counterpart of that series 
of bones in the harpy eagle, and departs but very little from 
what we find in other species. 
In our present subject the atlas lacks both neural and haemal 
spines, while the articular cup for the occipital condyle is 
notched above. Laterally, there may be a notch or a foramen 
for the passage of the vertebral artery upon either side. Its 
neural arch is rather broad, and the facet for the centrum of 
the axis is quadrilateral in outline, the width being twice that 
of the vertical height. At the middle point below, it is pierced 
longitudinally by a minute foramen; a broad notch being found 
at the same place in the atlas of the white-headed eagle. In 
this species, too, similar notches allow, in life, the passage of 
the vertebral arteries to the cranial cavity. Similar ones, though 
larger, are to be seen in the axis of Pithecophaga, in which 
vertebra are developed a stumpy haemal and a neural spine, as 
well as a more or less insignificant odontoid process. 
The neural canal throughout the cervical series of vertebrae is 
cylindrical in form and quite uniform in caliber. From the 
third to the twelfth vertebra, inclusive, the lateral foramina for 
