4g Philippine Journal of Science »i» 



base of the radial crest on the palmar aspect of the expanded 

 proximal end of this humerus ; it denotes the place of insertion, 

 in life, of the pectoralis muscle, and is found in the same location 

 in all true eagles. 



All of the ornithic characters seen in the avian humerus, in 

 so far as falconine species go, are to be found at the distal end 

 of this bone of our present subject, and each and all of them 

 are unusually prominent. This applies especially to the two 

 articular tubercles, the trachial fossa, and the tendinal grooves 

 on the anconal aspect. In the aforesaid fossa a few, small, scat- 

 tered, pneumatic foramina may be observed, especially just be- 

 yond the radial and ulnar tubercles. 



The radial crest of the left humerus of this individual exhibits 

 the results of some previous disease, and it has manifested itself 

 in the form of quite an extensive exostosis. The ulnar crest is 

 carried down onto the shaft for a distance of about a centimeter 

 as a sharp and distinct border; while at its middle we note a 

 small foraminal perforation, with a groove leading into or out 

 of it, on the palmar surface of the proximal, expanded extremity 

 of this bone. # 



This foraminal perforation is absent in the radial crest of the 

 humerus of the harpy eagle, and the crest itself is of a triangular 

 outline (Plate VII, fig. 2) ; while otherwise, in all other matters, 

 the two bones are notably similar in these two eagles. How- 

 ever, in the harpy it may be noted that the caliber of the shaft 

 is greater and presents less sigmoidal curvature. 



In the Korean eagle (Thallasoaetus pelagicus) the humerus is 

 fully 1.5 centimeters longer than it is in Pithecophaga jefferyi; 

 it is also straighter and somewhat slenderer. Its large, trian- 

 gular, radial crest extends farther down the shaft, while in all 

 other respects the two bones are very similar. Curiously enough 

 — the above fact notwithstanding — the skull of the Korean bird 

 is neither as large nor as massive as is the skull of the eagle of 

 the Philippines. This difference is possibly due to a longer wing 

 in the former species; but the material is not at hand at this 

 writing either to prove or to refute any such statement. 



In September, 1918, I published an account of Pithecophaga 

 jefferyi, illustrated by natural-sized figures of its head and foot. 1 

 In that article I made the statement that the species was the 

 largest of all existing raptorial birds. Possibly this may be so ; 

 while, upon the other hand, the big eagle of the Orient (Thalia- 



1 Am. Forestry 24 (1918) 555-557, 2 figs. 



