257 



would however have been interesting to know whether the mandibular 

 branch described by McKenzie lies internal or external to the palato- 

 quadrate apparatus. 



The external and internal carotids have separate and independent 

 origins from the eflerent glossopharyngeal artery, as described by 

 McKenzie, and from there run forward along the side wall of the 

 skull, the external artery lying dorsal to the internal one. When 

 they reach the hind edge of what Mc Murrich ('84) calls the posterior 

 division of the adductor arcus palatini, both arteries give off a small 

 branch. The branch from the external carotid accompanies the ramus 

 palatinus posterior of Herrick's ('01) descriptions, the branch from 

 the internal carotid going either to the adductor arcus palatini or 

 downward across the hind edge of that muscle to the dorsal surface 

 of the mouth; — probably to the former, for although I could not 

 definitely trace the artery it must be the posterior one of the two 

 branches that Mc Kenzie says are sent to the adductor arcus palatini. 



Immediately anterior to this little branch, above described, of the 

 internal carotid, the so-called pseudobranch begins and extends forward, 

 as Herrick ('01) has said, to the level of the opticus foramen. The 

 artery lies along the ventral, or ventro-lateral surface of this organ, 

 sending branches, or more properly lacunae, into it. At the anterior 

 end of the organ these lacunae are particularly large, and one of them, 

 which is directly continuous with the artery, gives origin to two 

 arteries, the larger one of which is the cerebralis while the other one 

 separates into two parts both of which go to the eye ball. The cor- 

 responding branches in Mc Kenzie's descriptions are said to arise from 

 the pseudobranch, the internal carotid itself being said to continue 

 forward ventral to the nervus opticus, and to distally become the 

 nasal artery; this entire horizontal portion of the main artery cor- 

 responding to the orbito-nasal artery of Allen's ('05) descriptions of the 

 Loricati, the short branch, or lacuna, that gives origin to the cerebral 

 and eye ball arteries being the cephalic trunk of those same descrip- 

 tions. In the Loricati the cephalic trunks of opposite sides unite to 

 from the median so-called encephalic or brain artery. In Ameiurus 

 they do not so unite, and as part of the trunk is not distributed to 

 the brain, it seems best to consider it, up to the point where it 

 separates into its two branches, as the direct continuation of the 

 internal carotid. 



The internal carotid, as above defined, after giving off its orbito- 

 nasal branch, turns upward and forward and immediately enters a 

 mass of dense connective tissue that surrounds the nervus opticus as 



Anat. Anz. XXXIII. Aulsätze. 17 



