54 
Philippine Journal of Science 
1919 
portions of which are upon the usual ornithic plan of the aqui- 
line pes, with the osteological characters I have often described 
before, of existing forms as well as of fossil eagles. 
CONCLUSIONS 
Coming to the relationships of Pithecophaga jefferyi , with 
respect to other representatives of the same group and in the 
light of the osteological material above described and compared 
with its skeleton, I am of the opinion that its nearest ally, in 
so far as we are at present acquainted with the morphology 
of other eagles, is the harpy eagle ( Thrasaetos harpy ja). 
Sharpe 2 makes a very different disposition of this species ; 
he places it between Circaetus and Spilornis, of the Aquilinse 
(Subfamily V) ; while the harpy eagle we find arrayed with 
the Buteoninse (Subfamily III), following Harpyopsis, the next 
following Subfamily (IV) being the Gypaetinse ( Gypaetus bar- 
batus) . The osteology of Pithecophaga surely does not support 
this arrangement. 
PREVIOUS PAPERS BY THE AUTHOR ON THE OSTEOLOGY OF THE 
EAGLES AND THEIR ALLIES 
[Papers on the owls and the vultures are not included.] 
1. On the ossicle of the antibrachium as found in some of the North 
American Falconidas. Bull. Nutt. Orn. Club 6 (1881) 197-203. 
2. On the free post-pubis in certain of the Falconidae. Auk 3 (1886) 133, 
134. 1 text figure. 
3. Osteology of Circus hudsonius. Journ. Comp. Med. and Surg. 10 (1889) 
126-159. 17 text figures. 
4. A peculiar character referable to the base of the skull in Pandion. 
Auk 8 (1891) 236, 237. 
5. Some comparative osteological notes on the American kites. Ibis VI 
3 (1891) 228-232. 
6. On a collection of fossil birds from the Equus beds of Oregon. Am. 
Nat. 25 (1896) 303-306. Plates. 
7. Fossil birds from the Equus beds of Oregon. Am. Nat. 25 (1891) 
818-821. 
8. Tertiary fossils of North American birds. Auk 8 (1891) 365-368. 
9. A study of the fossil avifauna of the Equus beds of the Oregon Desert. 
Journ. Acad. Nat. Sci. Philadelphia 9 (1892) 389-425, pis. 15-17. 
10. On cases of complete fibulas in existing birds. Ibis VI 6 (1894) 361-366, 
figs. 1, 2. 
11. Some of the “outliers” among birds. Pop. Sci. Monthly 44 (1895) 
760-780. 10 text figures (not osteological). 
12. On the affinities of Harpagornis. Trans. New Zealand Inst. 28: 665. 
13. Observations on the classification of birds. Proc. Acad. Nat. Sci. 
Philadelphia (1898) 489-499. Illustrated. (Osteology largely used.) 
’A Hand-list of the Genera and Species of Birds. London 1 (1899) 265. 
