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University of California Publications. [Geology 



their ventro-lateral angles form the posterior extremities of 

 the skull. The rear profile becomes concave in general, with the 

 median portion of the arc slightly interrupted by a gentle con- 

 vexity. The foramen magnum seems unique among known Rap- 

 tores. It lies in a plane facing as much backward as downward 

 and is decidedly deeper than wide. It has a sagittal diameter 

 of 14.3 mm., but measures only 11 mm. transversely across its 

 center. Toward the condyle it widens out slightly, so that it 

 appears bluntly pear-shaped in outline. The occipital condyle 



/ 



Figs. 1 and 2, Teratornis merriami. Fig. 1, Skull no. 12101 from below, 

 X %. Fig. 2, Skull no. 12101 from the rear, X A, postauditory pro- 

 cess ; B, basisphenoidal process ; C, cerebellar protuberance ; F, postfrontal 

 process; I, descending process of lachrymal; p, basipterygoid process. 



shows no peculiarity except possibly less tendency to form a 

 constricted neck than in most raptorial forms. Just forward 

 of the condyle, however, the basioccipital is excavated in two 

 very deep, rounded pits separated from each other by a low 

 median ridge. In front of this depression the basisphenoid rises 

 in an abrupt transverse ridge ending laterally in a pair of high 

 basisphenoidal processes. The whole region immediately ante- 

 rior to the condyle thus presents a very rugged topography. 

 The basipterygoid processes are well-marked fungiform struct- 

 ures placed far back upon the sphenoidal rostrum. This rostrum 

 is intact, and the interorbital septum is imperforate except at 

 the optic foramen (fig. 4). 



Viewed from the rear (fig. 2) the dome of the skull shows a 



