ILLUSTRATIONS 



[All the figures are reproductions of photographs by the author made direct from the 



specimens.] 



Plate I 



Fig. 1. Pithecophaga jefferyi, adult; right lateral view of the skull, 

 natural size. All the bones of this bird figured on the plates 

 are of two individuals. The specimens were received from 

 Mr. R. C. McGregor, of the Bureau of Science, Manila, P. I. 

 2. The skull shown in fig. 1, seen directly from above, natural size. 



Plate II 



Fig. 1. Hali&etus leucocephalus, white-headed eagle, sex?, adult; cranium, 

 direct view from above, very slightly reduced. Median lon- 

 gitudinal diameter measures 11.1 centimeters in this specimen. 

 No. 19278, United States National Museum collection. This 

 skull belongs to the skeleton of the specimen used throughout 

 this paper. 



2. Aquila chrysaetos, female, adult; cranium, direct view from above, 



very slightly reduced. Median longitudinal diameter measures 

 11.9 centimeters in this specimen. No. 18802, United States 

 National Museum collection. 



3. Morphmis gttianensis, sex?, adult; cranium, direct view from above, 



very slightly reduced. Median longitudinal diameter measures 

 9 centimeters in thia specimen. No. 18468, United States 

 National Museum collection. 



Plate III 



[All figures of Plate III natural size and from the same species, Pithecophaga, jefferyi.] 



Fig. 1. The six caudal vertebras (a to 6) arranged in normal sequence 

 and viewed from above; a, anterior one of chain. 



2. Pygostyle, right lateral aspect. Lower part pierced by a foramen. 



3. Fifth cervical vertebra, seen from above. 



4. Mandible, seen from above. 



5. Anterior aspect of ninth cervical vertebra. 



6. Trachea, twisted and distorted through drying; fragments of 



bronchial tubes at inner end. 



7. The atlas, posterior aspect. 



8. Anterior view of axis; neural spine directed downward. 



9. Sclerotal circlets of the eyes; elements as they occur or are 



arranged in life. 

 10. Hyoid arches viewed from above, with larynx in situ; the latter 

 removed at a point seen at the outer end of the trachea in fig. 6. 



Plate IV 



Pithecophaga jefferyi; right lateral view of the trunk skeleton, including 

 bones of the shoulder girdle, reduced about one-third. The 

 pygostyle and the six caudal vertebrae preceding it have been 

 removed. 



57 



