Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 135 



mesially enclosing a triangular, depressed portion of the roof of 

 the branchial cavity. The dermal portions of all these bones have 

 not the some color and texture as the underlying cartilage bones, 

 but they cannot be separated from them without facture. 



The third infrapharyngobranchial has a pointed anterior end 

 and a straight posterior edge. From the mesial portion of the 

 latter edge a strong process projects posteriorly. The pointed 

 anterior end of the element is capped with cartilage and overlaps 

 and lies against the postero-mesial surface of the second infra- 

 pharyngobranchial. Starting from this end of the element, and 

 running backward across its entire dorsal surface, there is a 

 strongly raised portion, the hind end of which forms the lateral 

 edge of the posterior process of the element. At about the middle 

 of the length of the ridge there is a slight eminence, and at its 

 hind end a large and strong one. The outer surfaces of both 

 eminences are directed upward, backward, and slightly laterally, 

 and are capped with cartilage. The anterior one gives articula- 

 tion to the posterior portion of the articular head of the second 

 epibranchial. The posterior one lies lateral to the posterior proc- 

 ess of the element and gives articulation to the epibranchial of 

 the third arch. The posterior process of the element is capped 

 with cartilage and overlaps dorsally the fourth infrapharyngo- 

 branchial, the cartilaginous cap of the process resting upon a 

 cartilaginous portion of the fourth infrapharyngobranchial. It 

 does not give articulation to any structure. 



The fourth infrapharyngobranchial has a straight anterior 

 edge, and from there tapers gradually backward, with slightly 

 convex edges, to a bluntly rounded posterior end. From the 

 mesial corner of its anterior edge a long and slender process pro- 

 jects forward and overlaps the mesial edge of the hind part of the 

 third infrapharyngobranchial. Slightly posterior to the anterior 

 edge of the piece there is, on its dorsal surface a wide transverse, 

 raised strip of cartilage. The mesial end of this strip is hollowed 

 out, and receives the overlapping end of the posterior process of 

 the third infrapharyngobranchial. The hind edge of the strip 

 of cartilage on the fourth infrapharyngobranchial is usually here 

 exposed. The lateral and larger part of the strip is concave 

 dorsally and gives articulation to the anterior portion of the prox- 



