302 Mr. D. M. S. Watson on 



insertions pointing forwards and downwards into the tcm- 

 [)Oj-al fossa, and its surface bears faint furrows with tlie same 

 trend. 



The periotics and basisphenoid are not separated by recog- 

 nizable sutureSj and are therefore almost necessarily described 

 together. 



The under surface of the basisphenoid is slightly cmeavei 

 it bears a low median ridge and also two curious and feebly 

 marked pits which do not appear to lead into foramina 



At the extreme back the basisphenoid, with the periotic, 

 exoccipital, and basioccipital, forms a large deep pit on each 

 side; these pits are provided with a small channel leading 

 outwards and downwards, and also receive at least two fora- 

 mina — a large foramen leading upwards and presumably 

 opening into the brain-cavity directly, and a very small 

 foramen which opens into the pit at the back just in front 

 and rather to the outside of the occipital condyle ; this last 

 foramen appears to traverse the very thin lamina of ex- 

 occipital which forms the posterior wall of the pit at this 

 point, and open by a minute foramen just outside the 

 condyle. 



It is probable that the large foiamen is further divided, 

 but the matrix filling the cavity is too luird to admit of 

 further development. 



The outer wall of this pit is thin and forms part of a more 

 or less vertically placed area (Hg. 6j. This area is divisible 

 into two — a small oval space, whose long axis lies almost 

 horizontally but slightly depressed in front, which forms a 

 deep hollow whose bottom is penetrated by a small nearly 

 circular foramen, less than 2 mm. in diameter, which can 

 only be the fenestra vestibuli seu ovale. 



The other part of the area is rather more vertically placed, 

 lies dorsal to the oval space, and is not well preserved. 



The whole area is separated by a very distinct rectangular 

 corner from the smooth, concave, cylindrical face of the 

 paroecipital process. 



In front of this area the basisphenoid and the periotic form 

 a smooth vertically placed face, inclining strongly inwards 

 anteriorly ; this face is pierced by a foramen just in front of 

 the area surrounding the fenestra vestibuli. This very 

 small foramen can only have transmitted the seventh nerve. 

 The anterior border of this vertical face is made by a deep 

 notch, above which the bone is continued as a long process 

 (iig. ()). This notch is undoubtedly the hypapophysial fossa, 

 for the pituitary and the internal carotids no iloubt entcreil 



