I50 



ALUS. [Vol. XVIII. 



hence ventral to the dorsal end of the infrapharyngobranchial of 

 the first arch, traverses the internal carotid foramen and enters the 

 eye-muscle canal. There it continues forward to the anterior edge 

 of the basisphenoid, where, lying quite close to the middle line 

 of the head and not far from its fellow of the opposite side, it 

 turns upward, along the anterior edge of the basisphenoid, and 

 enters the cranial cavity, its further course not being traced. 

 Before leaving the eye-muscle canal it has a delicate commissural 

 connection with the arteria ophthalmica magna, as already stated. 



No branch could be found corresponding to the hyo-opercularis 

 of my descriptions of Amia. 



The arteria hyoidea arises, as in other teleosts, from the distal, 

 or antero-ventral end of the efferent artery of the first arch, and 

 is a direct anterior continuation of that artery. Running forward 

 it traverses the canal that perforates the hypohyal between its two 

 ossifications, and reaches the external, or ventro-lateral surface 

 of that element. There it turns almost directly backward and 

 laterally, and runs proximally along the hyoid arch, lying in the 

 groove that begins on the hypohyal and continues backward along 

 the ceratohyal near its dorsal edge. When the artery arrives near 

 the proximal end of the ceratohyal it turns upward, slightly in 

 front of the epihyal, and enters a fold of skin that extends from 

 the ceratohyal to the inner surface of the palato-quadrate arch. 

 Traversing this fold it enters the slit-like opening that is found 

 between the hind edge of the symplectic and the anterior edges of 

 the preoperculum and the dorso-posterior process of the quadrate, 

 and, traversing it, reaches the outer surface of the adjoining ends 

 of the symplectic and hyomandibular. There it sends a branch to 

 the deeper part of the adductor mandibulse muscle, and then 

 traverses the opening between the anterior edge of the hyoman- 

 dibular and the hind edge of the metapterygoid, and reaches the 

 inner surface of the hyomandibular. There it runs upward, be- 

 tween the hyomandibular and the overlapping posterior process of 

 the metapterygoid, and reaches and enters, as its afferent artery, 

 the anterior end of the opercular demibranch. 



From the anterior end of the opercular demibranch the efferent 

 artery of that structure arises, and, as the arteria ophthalmica 

 magna, runs forward along the lateral surface of the skull and 



