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end of the first efferent branchial artery. From there the artery runs 

 downward and forward external to the common carotid prolongation 

 of the lateral dorsal aorta, and soon gives off a branch which enters 

 the trigemino-facialis chamber by its facialis opening and, while in 

 that chamber, unites with the ophthalmicus branch of the external 

 carotid, described below. The hyo-opercularis, after giving off this 

 branch, turns downward, and, having sent a branch to the opercularis 

 and hyomandibularis muscles, traverses the facialis canal through the 

 hyomandibular, sends a second branch to the opercularis muscles and 

 still others to the latero-sensory canals and then becomes continuous 

 with the secondary afferent hyoidean artery, already described, thus 

 forming a complete arterial arch in the hyoidean arch. 



The common carotid artery, or prebranchial portion of the lateral 

 dorsal aorta, runs forward and soon separates into its internal and 

 external branches. The internal carotid has the course and the con- 

 nection wdth the efferent pseudobranchial artery given in my earlier 

 work (Allis 1897), and needs no further description here. The 

 external carotid enters the trigemino-facialis chamber through the 

 external carotid foramen, and while in that chamber gives off an 

 orbital branch. This orbital branch separates into two branches one 

 of which issues from the trigemino-facialis chamber through its trige- 

 minus foramen and supplies the recti externus, inferior and superior 

 muscles and general tissues in the ventral portion of the orbit, while 

 the other fuses with that branch of the hyo-opercularis, just above 

 described, that enters the trigemino-facialis chamber. The single 

 artery formed by the fusion of these two vessels then issues from 

 the chamber through its ophthalmicus foramen and, accompanying 

 the ophthalmicus nerves, supplies the obliqui superior and inferior 

 and rectus internus muscles, sends branches to the latero-sensory 

 canals and then enters the nasal capsule and there anastomoses with 

 the olfactory branch of the internal carotid. 



The external carotid, after giving off its orbital branch, issues 

 from the trigemino-facialis chamber through its trigeminus foramen 

 and then soon sends a branch downward and backward to the pseudo- 

 branch, this branch being the secondary afferent pseudobranchial 

 artery of my descriptions of embryos. The remaining, maxillo- 

 mandibular portion of the carotid, called by Allen, in Ophiodon, the 

 facialis-maxillary branch of the artery, then sends a branch to ac- 

 company the maxillaris nerve, sends one large and other smaller 



