154 THE SKULL. [CHAP. 



near its anterior, the other near its posterior border. Close 

 behind the last named is a small hole (" foramen spinosum "), 

 through which a branch of the external carotid artery 

 (middle meningeal) enters the brain-cavity. 6 and 8. The 

 foramen lacerum medium basis cranii and the foramen 

 lacerum posterius have the same functions and relation as 

 in the Dog. 7. Between these two the periotic has the 

 conspicuous meatus auditorius internus on its inner side- 

 The depression above this, for the lodgment of the floc- 

 culus, is distinctly seen in fcetal human skulls up to the 

 time of birth, but it afterwards becomes gradually oblite- 

 rated. 9. The condylar foramen perforates the exoccipital, 

 as in the Dog; and lastly (10), the foramen magnum has 

 the same general subcircular form, and is bounded by the 

 same bones, but differs greatly in direction, its plane looking 

 mainly downwards instead of backwards. 



The nasal cavities differ chiefly from those of the Dog in 

 their shortness and greater vertical height. In their inner 

 wall, the descending median plate of the vomer ( Vo) is 

 much more developed. The pterygoids (Pi) are extended 

 vertically, are narrow from before backwards, end below in 

 a marked " hamular " process, and soon ankylose with the 

 pterygoid plates of the alisphenoid anteriorly, but posteriorly 

 are separated from them by a well-marked " pterygoid 

 fossa." l The palatines (PI) and maxillae (Mx) are short 

 from before backwards. The premaxillae (PMx) are small 

 and early ankylosed with the maxillre. 2 The nasals (Net) 



1 The pterygoid, not being recognised as a distinct bone, is commonly 

 described in works on human anatomy as " the internal pteryrroid plate 

 of the sphenoid ; " the pterygoid process of the alisphenoid being the 

 "external pterygoid plate." 



2 The premaxilla is a distinct bone in the human foetus, but is covered 

 on its external or facial aspect by a process of the maxilla, which extends 

 over it towards the middle line, and becomes completely fused with it 



