OSTEOLOGY OF BIRDS I 9 



and concave from above downward in Cathartes a. septen- 

 t r i o n a 1 i s and Cat h arista urubu, less so in G y p a r - 

 chus papa, while in Gymnogyps and the South American con- 

 dor it is nearly flat and slopes away rapidly toward the sphenoidal 

 suture, being marked by several transverse lines or ridges. The 

 " foramen ovale " is unusually large as a rule in these birds, and is 

 to be found rather low down in the orbit, almost hidden in the 

 shadow of the great quadrate bone on either side. 



Posteriorly, the cerebellar prominence is a feature in the crania 

 of all these American vultures. This is strikingly the case in 

 Gymnogyps, in which species, as among certain others of the 

 Cathartidae, the inferior border of this elevation of the occiput and 



Fig. i Posterior view of the cranium of G y m - 

 nogyps calif ornian u-s ; life size and 



mandible removed. Sp, the apophysial projections, 



one upon either side of the posteroexternal angles of 

 the basitemporal 



the superior arc of the foramen magnum are in the same curved 

 line, which line slopes away on either side to terminate in the par- 

 occipitals or lower angles of the raised osseous ridges that bound 

 the ears. This line or ridge forms a striking feature in the rear 

 views of the skulls of the Cathartidae, and is present to a greater 

 or less extent in many of the diurnal and nocturnal birds of prey. 

 The occipital condyle, which has already been alluded to above, is 

 found to be generally larger throughout the vultures than in the 

 Falconidae. We show in our cut of the rear view of the cranium 

 of Gymnogyps [fig. i|, how the. region of the occiput is bounded 

 by the superior muscular line, both laterally and above ; this line is 

 well marked in all of these vultures. The lines at the sides are 



