1 8 ALLIS. [Voi,. I. 



cavity proper by this foramen. After its exit from the brain it 

 pierces a mesial membranous part of the anterior wall of the 

 labyrinth recess, enters the upper lateral chamber of the eye- 

 muscle canal, where it traverses the trigemino-facial ganglion, 

 and then issues from the skull by the large facial foramen. 

 Slightly below this foramen, and hence what would be in the 

 human skull mesial to it, are the external carotid foramen and 

 the external orifice of the internal carotid canal. Internal to 

 the foramen, in the upper lateral chamber of the eye-muscle 

 canal, the palatine branch of the facialis enters the posterior 

 orifice of a canal, called in my descriptions the palatine canal, 

 which runs forward between the parasphenoid and the ventral 

 surface of the chondrocranium. 



It is thus evident that but for the fact that the main external 

 carotid artery of Amia enters the upper, lateral chamber of 

 the eye-muscle canal, while in man its meningeal branches 

 only enter the skull, there would be a striking functional 

 resemblance between the facial and carotid foramina united, 

 of Amia, and the foramen lacerum and jugular foramen 

 together, of man. Moreover, that the difference in the course 

 of the external carotid in the adult of Amia and of man is 

 probably not of morphological importance, is evident from the 

 fact that in embryos of the higher vertebrates (No. 27, p. 66) 

 the external carotids have an intracranial course. Further- 

 more, what may possibly be related to that early condition, an 

 external carotid may be, in rare cases, wanting even in the adult 

 man (No. 24, vol. ii, pt. ii, p. 393). 



In teleosts the same general relations of the parts here under 

 consideration are found as in Amia, but there is great varia- 

 tion in the details of the disposition of the several parts, and 

 the resemblances to the conditions found in man are not so 

 striking as in Amia. The jugular foramen may become either 

 partly or entirely separated from the facial foramen ; the two 

 carotid arteries may enter the eye-muscle canal by a single 

 foramen, corresponding in position to the internal carotid fora- 

 men of Amia; and the facialis may have its exit by two 

 foramina instead of by one (No. 27, p. 65, and No. 28, p. 559). 



The trigemino-facial ganglion in Amia lies in the upper, 



