Vol. 5] 



M iller. — Terator nis . 



309 



very flat, regular curve, gradually increasing; laterally as the 

 postfrontal processes are deflected more abruptly at their ends. 

 There is no tendency toward the longitudinal furrowing in the 

 region of the cerebrum that is noticeable in many recent accip- 

 itrines. 



The occipital region is marked by a well-defined transverse 

 ridge passing across from one postauditory prominence to the 

 other and curving gently upward to form the dorsal border of 

 the foramen magnum. This transverse ridge is the angle of 

 intersection of two slightly concave surfaces, a postero-dorsal 

 and a postero-ventral slope. The ventral surface, trending for- 

 ward and downward, includes the plane of the foramen mag- 

 num and a nearly smooth ex-occipital surface on either side of 

 it. The whole postero-ventral surface is remarkably uniform in 

 its concavity and almost unbroken, except as interrupted near 

 its center by the abrupt rise of the occipital condyle and by 

 the basioccipital depressions. Above the transverse ridge the 

 postero-dorsal area slopes forward and upward to a limiting, 

 transverse intermuscular ridge near the dorsal profile of the 

 skull. Across its middle passes a second transverse intermuscular 

 ridge and down its median sagittal line an abrupt vertical crest, 

 the cerebellar protuberance. The lateral terminations of the 

 upper limiting crest are almost confluent with the temporal 

 crests. Thus the whole posterior aspect of the skull must have 

 been hidden by the powerful musculature of the head and neck. 



From above (fig. 3), the great flatness of the skull is again 

 evident, although its roof is gently convex on the whole in any 

 vertical section. Even in the region of the lachrymals the me- 

 dian line is not depressed below the orbital borders. A very 

 slight downward tendency is shown at the region where the 

 nasals begin, but beyond this point the parts are wanting. 

 There is positive indication, however, of a high "bridge of the 

 nose" as in Cathartidae and in contrast with falconids (figs. 9, 

 10, 11). 



The masseteric depressions lie largely upon the top of the 

 skull in a plane approaching the horizontal (fig. 3). In Cathar- 

 tidae and Falconidae these areas lie in the lateral and posterior 

 aspects of the skull in a more nearly vertical plane. 



