ately in front of the exoccipital is an oval foramen between 

 that bone and the opisthotic through which the tenth and 



Although morphologically this is the equivalent of the 

 jugular foramen of the mammalia; situated as it is between 

 the opisthotic, lower portion of petrosal ami the exoccipital; 



extent anatomically misleading to designate it "jugular 

 foramen," hence the name I have adopted. 



In front of the vago-accessory foramen is a big dificiency 

 in the side wall of the cranial cavity (hiatus acusticus) due 

 to the incomplete ossification of the periotic bones. So 

 large is the aperture so formed that one can examine the 

 whole of the cavities of the osseous Inbyrynth without any 

 dissection (See especially figure 49). 



Seen through the aeustie hiatus the fenestra rotunda [34] 

 is situated just in front of and below the vago-accessory 

 foramen bounded above and in front by the incisura rotunda 

 below and behind by basi- and exoccipital bones. The 

 much larger fenestra ova I is [33 1 is separated from the 

 fenestra rotunda by the interfenestrnl process [35] of the 

 opisthotic, is bounded in front by the prootic, and is incom- 

 plete below. The glossopharyngeal canal (canal is alossa- 

 phavijnaeus) [29] perforates the base of the interfenestral 

 process nearer the rotund than oval fenestra. Hoffmann, 

 quoting Hasse, designates this canal 'aquednctus cochleae'; 

 it certainly transmits the ninth nerve, and I have been 

 unable to find a reason for the name applied by Hasse. The 

 main cavity exposed by the hiatus is the vestibular cavity 

 the prootic recess above and in front of the fenestra ovalis 

 (recessus vestibularis prooticus) lodges the utricular recess, 

 and has opening into it the horizontal and anterior semi- 

 circular canals, the opisthotic recess (recessus vestibularis 

 opisthoticus) lodges the posterior utricular sinus, and has 



