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a part of the external carotid, is a short artery which runs forward, 

 and then forward and laterally immediately beneath the base of the 

 skull. It passes ventral to the glossopharyngeus foramen and then 

 immediately separates into its two parts, the internal and external 

 carotids, the external artery being much the larger of the two. The 

 internal carotid was, as already stated in an earlier work (Allis, 1908), 

 considered by Allen as a commissure connecting the external carotid 

 and efferent pseudobranchial arteries, the latter artery being called by 

 Allen the anterior or internal carotid. 



The external carotid, as it separates from the internal one, turns 

 laterally and upward and traverses a foramen in the cranial wall that 

 has exactly the position of the external carotid foramen in Amia. In 

 Polyodon, as in Amia, the foramen lies slightly posterior to the hind 

 edge of the ascending process of the parasphenoid, and it undoubtedly 

 is the one shown in that position, but without index letter, in Bridge's 

 figures 2, 3 and 4. 



The foramen, in larvae, opens directly into the "short antero- 

 posterior", or "facial" canal of Bridge's descriptions, and directly 

 opposite this foramen the cranial wall of the canal is pierced by an- 

 other foramen which opens into the auditory recess of the cranial 

 cavity. This second foramen is apparently the one marked 2 in 

 Bridge's figure 6 ; but as this index figure 2 is not given in Bridge's 

 descriptions of his plates, it seems probable that the foramen so 

 indicated is the foramen s which is referred to in the text but not 

 shown on any of the figures or given in the list of index letters. Of 

 this foramen s Bridge says (p. 699): "Whether the foramen marked 

 s in Fig. 6 is for the pre-spiracular nerve, or, as is more probable, 

 simply transmits a vessel, I am unable to say". In one of my specimens 

 the foramen was traversed by two small branches of the hyo-opercularis 

 branch of the external carotid, while in a second specimen it was not 

 traversed by anything whatever. 



The external carotid, having traversed the foramen in question 

 and entered the facialis canal, immediately gives off the hyo-opercularis 

 branch just above referred to, which branch runs backward in the 

 facialis canal, accompanying the hyoidean branch of the facialis nerve 

 and the jugular vein, and issues with those structures from the 

 posterior opening of the canal, this opening being the foramen marked 

 VII in Bridge's figure 2 and Vll' in his figures 3 and 4. The external 

 carotid itself turns forward in the facialis canal, where it lies ventro- 

 lateral to the hyoideus facialis nerve and ventro-mesial to the jugular 

 vein. Slightly anterior to the external carotid foramen the r. hyoideus 

 acialis perforates the cranial wall of the facialis canal and enters the 



