Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 133 



portion of the lateral surface of the skull, lying, when at rest, im- 

 mediately in front of, or immediately external to, the internal 

 carotid foramen, and immediately behind the posterior edge of the 

 surface of insertion of a part of the united and continuous adductor 

 hyomandibularis and adductor arcus palatini muscles. The lateral 

 surfaces of the parasphenoid and petrosal are here slightly 

 grooved, where the infrapharyngobranchial rests against them, 

 the proximal end of the latter bone reaching about to the inferior 

 edge of the facial foramen, where it is bound to, and articulates 

 with, the skull. The proximal end of the bone lies immediately 

 ventral to the ventral edge of the opercular demibranch, and, when 

 pulled backward, encloses the internal carotid artery between it- 

 self and the side wall of the skull. The external carotid lies 

 wholly dorsal to it. The cartilaginous, inferior end of the element 

 is hollowed slightly, and articulates with the rounded proximal 

 end of the first epibranchial, the hollow of the infrapharyngo- 

 branchial being presented ventrally, laterally and posteriorly. 



In Amia (No. 4) the common carotid artery runs forward ven- 

 tral to the first infrapharyngobranchial, and separates, beyond 

 that bone, into its external and internal portions. The internal 

 carotid alone of Scomber retains this relation to the infrapharyngo- 

 branchial, the external carotid having apparently slipped upward, 

 between the infraphar3'ngobranchial and the side wall of the skull, 



In my notes I find reference to some fish, I can not recall which, 

 in which a ridge is described on the lateral surface of the skull, in 

 a position corresponding to that of the first infrapharyngobranchial 

 of Scomber, and which might accordingly be that bone fused with 

 the skull. 



The Second Infrapharyngobranchial (IPB, II) is a flat, 

 irregular bone, which, in its natural position, lies in a plane in- 

 clining downward, forward and laterally. In Fig. 29 it has been 

 pulled somewhat out of its natural position and is shown inclin- 

 ing downward and backward instead of downward and laterally. 

 Its inferior edge is slightly curved and is covered with dermal bone 

 which is furnished with numerous bristles. It forms the anterior 

 one of the two superior pharyngeal bones on each side of the head 

 of the fish. The bristles it bears are smaller and shorter than 

 those on the posterior bone. The superior, or antero-lateral sur- 



