Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 137 



anterior cartilaginous portion of the dorsal edge of the second 

 infrapharyngobranchial. It lies, as already stated, ventral to the 

 efferent artery of its arch, and probably ventral also to the dorsal 

 end of the afferent artery, but its relations to the latter artery were 

 not satisfactorily traced. 



No suprapharyngeal elements were found on the other arches. 

 The postero-mesial processes of the second and third epibranchials 

 are, however, like the corresponding processes in Amia (No. 4, 

 p. 663), suprapharyngeal in position. 



4. Hyoid Arch. 



The hyoid arch of Scomber contains, in addition to the so-called 

 basihyal, three separate pieces, which articulate one with the 

 other, the proximal piece articulating with the lateral surface of 

 the skull by two articular heads. This proximal piece contains' 

 two ossifications, the hyomandibular and symplectic, connected 

 with each other by a small interspace of cartilage. The middle 

 one of the three separate pieces of the arch, the interhyal, articu- 

 lates with the interspace of cartilage between the hyomandibular 

 and symplectic, and has, as in Amia (No. 4, p. 653), the position 

 of an epal element of the arch. The distal one of the three sepa- 

 rate pieces is large, long and flat, with its long axis lying in a 

 nearly horizontal position and its transverse axis inclining down- 

 ward and slightly mesially. The anterior end of its superior edge 

 lies slightly dorsal to the corresponding edge of the first branchial 

 arch; the posterior end somewhat ventral to the outer end of the 

 same arch. It contains four separate ossifications, two of which 

 form the hypohyal of current nomenclature, and the other two 

 the ceratohyal and epihyal. For reasons given in my work on 

 Amia (No. 4, p. 654), I consider the last two ossifications as the 

 proximal and distal ossifications of the ceratohyal. Between 

 the hypohyal and the ceratohyal, as thus defined, there is a definite 

 surface of separation, but tough fibrous tissue, which is apparently 

 in part the periosteum or perichondrium of the structure, passes 

 over the separating line, and so firmly unites the two pieces that 

 only a slight movement is possible between them. The surfaces 

 by which the two elements thus articulate are each separated into 

 three parts, two of which are transverse to the piece and the other 



