112 INSEOTIVOEA. 



and tlie foramen magnum looks downwards and backwards, but much more in 

 tlie latter than in the former direction. The condyles look outwards, forwards, and 

 downwards. There is a very minute rudiment of a para-occipital process,' and more 

 distinct indications of a mastoid protuberance. The meatus auditorius externus looks 

 outwards and slightly upwards. The tympanic bullae are entire, and no portion of 

 the basi-sphenoid contributes to form them. There is a distinct basi-occipital ridge, 

 but it is not continuous with the well-marked ridge of the mesopterygoid fossa. A 

 small post-glenoid process contributes to complete the anterior border of the meatus 

 auditorius externus. The auditory bullae are placed obliquely across the base of 

 the skull, being divergent posteriorly and convergent anteriorly, in which direction 

 they taper to a point which is in the same line with the lateral wall of the meso- 

 pterygoid fossa. The glenoid articular surface is almost flat, but slightly concave> 

 where it is overlooked by the post-glenoid process. The mesopterygoid fossa con- 

 tracts from before backwards, but its broadest diameter corresponds to the interval 

 between the anterior extremities of the auditory bullae. Its anterior two-thirds is 

 marked by a pronounced median vomerine ridge, which is partially prolonged on to 

 the basi-sphenoid. The ectopterygoid plate is small, pointed and falcate, and is 

 directed downwards, backwards and outwards, and is perforated at its base by a canal. 

 The pterygoid fossa is small, and is separated from the palate by a ridge of bone as 

 long as the longitudinal extent of the fossa. There are one or two minute circular 

 imperfections in the basi-sphenoid. The palatal surface is concave from before 

 backwards, and from side to side, and an obscure osseous ridge runs along the 

 median line. 



There are a number of imperfections in the posterior third of the palatal surface. 

 The posterior margin of the palate is distinctly thickened, forming a ridge of more 

 compact osseous tissue than the rest of the palatal surface. That portion of the 

 margin corresponding to the mesopterygoid fossa is doubly concave from behind 

 forwards, each concavity corresponding to one-half of the fossa. The portion of the 

 margin external to this is convex from before backwards, and projects backwards 

 about half the diameter of the last molar beyond that tooth. The first and second 

 premolars are separated by a short interval corresponding to the distance, or nearly 

 so, that intervenes between the first and second incisors, and the canine is removed 

 from the second incisor by about double that distance. Viewing the skull sideways, 

 the alveolar margin arches upwards as far as the canine, and then, in a long, shghtly 

 convex sweep, goes downwards as far as the posterior margin of the second molar, 

 beyond which it is directed upwards and inwards. 



There is a rather large supra-orbital foramen at the point where the contraction 

 between the orbits is most marked, and a smaller infra-orbital foramen above the 

 second premolar. There are two small foramina placed one above the other on the 

 parietal above the zygoma and the meatus auditorius externus, and both open into 

 the moderately large foramen behind the post-glenoid process. A similar foramen 



* Mivart did not observe one in the skulls he examined. 



