1902. J OSTEOLOGY OP THE FALCONIFORMES. 283 



The Squamosal Prominence. — In the more primitive forms, 

 such, as Serpeniarius, Polyhoroides, and Pernis, the squamosal 

 prominence is very feebly developed. As usual, its inferior 

 sui'face affords a glenoid cavity for the articulation of the squamosal 

 head of the quadrate, Mesiad of this glenoid cavity is the aperture 

 of the superior tympanic recess. The zygomatic process is very 

 small ; in Serpentarius it is wanting. 



The squamosal prominence is seen at its best in the Falconidse 

 (including Polyhorxhs), where it projects conspicuously fi'om the 

 skull-wall. The zygomatic process is excessively developed in 

 Polyhoriis^ where it hangs downwards, eaves- fashion, over the 

 quadrate. In addition to this, is a second and equally large 

 process depending from the antero-lateral angle of the lateral 

 occipital wing, at its junction with the zygomatic process. 



The postero-inferior angle of the squamosal, in Polyhoroides 

 and in the Falcons, develops a large, downwardly-directed and 

 pointed spike— the processus articularis squamosi. Between this 

 and the zygomatic process just described, the squamosal head of 

 the quadrate is tightly grasped. In Serjientarius, the Eagles, 

 Per7iis, Pandion, Buteo, Circus, Gypaetos, and many of the true 

 Vultures, for instance, this articular process is but feebly 

 developed. In Oathartte it is wanting. 



The temporal fossce are for the most part but shallow, linguiform 

 dejDressions in the parietal region of the skull, and which never 

 extend backwards to meet the mid-dorsal line. In Serpentarius 

 they are exceedingly shallow and scarcely rise above the level of 

 the base of the postorbital process. They are best developed in the 

 Falcons and Polyhoi^us, where they extend inward to within a 

 a short distance of the cerebellar prominence. 



The trigeminal foramen is completely isolated, lying far removed 

 from the mouth of the superior tympanic recess, and considerably 

 in front of a line drawn transversely tlu'ough the skull across the 

 squamosal head of the quadrate. 



The orbits are large. In Serpentarius they are protected from 

 above by wide overhanging ledges formed by the frontal bones, 

 behind, and by large, horizontal, backwardly-dii'ected, flattened 

 plates developed by the lachrymal, in front. These, one on either 

 side, fit closely to the frontal. In the higher Accipitres the width 

 of the interorbital region of the frontals is much less, the free 

 edge forming a deep hollow. In this case the horizontal process 

 of the lachrymal is left as an isolated spur projecting on either 

 side of the roof of the skull and overhanging the orbits. In the 

 majority of such cases, the length of the spur is increased by 

 the addition of a separate scale- shaped ossicle — the superciliary 

 ossicle. This is attached to the lachrymal by connective tissue. 

 In the Falcons and Vultures it fuses with the laclirymal. In the 

 Cathartse the supra-oi-bital limb of the lachrymal is suppressed, 

 the lachrymal itself fusing completely with the frontal. 



The orhito-sj)henoid is completely ossified in all the Falconi- 

 formes, 



19* 



