9 Right lateral view of the skull of Cathartes a. septen- 

 trional is, including the mandible, which latter is detached. 

 Natural size, from an adult specimen 



10 Right lateral view of the skull of Neophron percnop- 

 t e r u s ; mandible detached. Natural size. See remarks under 

 plate 5, figure 8 



1 1 Right lateral view of the skull of Buteo borealis 

 calurus ; mandible detached. Natural size. The accessory 

 piece on the lacrymal bone is taken very black in the picture, and 

 must not be mistaken for a foramen in the interorbital septum, there 

 being but one central, elliptical aperture of the kind in that osseous 

 partition between the orbits. 



148 



