THE HEAD. 85 



If one of the branches of a goniometer be placed tangentiallj to the surface 

 of the basilar process, and the other to the summit of the external occipital 

 tuberosity, the basilo-occipital angle will be obtained. In the measurements 

 we have taken of eight heads of Horses of diverse ages and breeds, this angle 

 has varied from 70° to 91°. We except the head of a young English Stallion, 

 the basilo-occipital angle of which was from 92° to 100°. Measurement of the 

 heads of Asses showed the angle to be 103°. The average basilo-occipital angle 

 was 85*36° for the Horse, and 95° for the Ass. 



If, instead of taking the basilo-occipital angle, the goniometer be applied to 

 the origin of the temporal crests and the superior outline of the occipital 



Fig. 52. 



ass's head (lateral face). 



, Occipital condyle ; 2, styloid process of the occipital bone, with a very marked furrow on its 

 external face; 3, external occipital tuberosity, more developed than in the horse; 4, parietal 

 crest ; 5, external auditory hiatus ; 6, zygomatic process of the temporal bone ; 7, frontal bone ; 

 8, orbit, with its external outline more angular than in the horse; 9, lachrymal bone, with its 

 tubercle partly implanted on the nasal bone; 10, zygomatic or malar bone; 11, nasal bone; 

 12, supermaxilla ; 13, zygomatic spine; 14, infra-orbital foramen; 15, premaxillary bone, with 

 its inner border raised by a salient tubercle above the incisive canal ; 16, incisor teeth ; 17, 

 molar teeth; 18, inferior maxilla; 19, maxillary fissure; 20, maxillary condyle; 21, coronoid 

 process ; 22, mental foramen ; 23, supra-orbital foramen, carried more to the middle of the orbital 

 process than in the horse ; 24, basilar process of the occipital bone. 



In the Horse, this angle is 

 and S7° — the average being 



foramen, the parieio-occipifal angle is obtained 

 between 81° and 104° ; in the Ass between 7' 

 91-12° for the Horse, and 84° for the Ass. 



It was foreseen that the value of these angles would be in inverse relation. 

 In all cases when, on a head, the basilo-occipital angle was found very open and 

 the parieto-occipital more closed, combined with a great development of the 

 external occipital tuberosity and the differential characters already described, 

 it was certain to be the head of an Ass. In the English Horse, the external 



