COMPARATIVE STUDY OF SCOMBROID FISHES. 
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Tlie ceratobranchials are very long, subequal in length, more or less curved 
upward, and grooved on the ventral side. They are narrow in the Scombridæ, 
and narrow and compressed in the Cybiidæ, especially in Acanthocybium. In 
the Thunnidæ they are more or less compressed at the anterior portion, but 
rather flattened at the posterior. In the Katsuwonidæ they are more flattened. 
The epibranchials are short, much curved, and often twisted. They are 
rather elongated in the Cybiidæ. The curving and twisting of these ossicles 
are remarkable in the Scombridæ ; but they are rather elongated in the 
Cybiidæ. 
The upper and lower pharyngeals are broad in the Scombridæ, but in 
the other scombroid fishes they are narrow. 
Pectoral Girdle. 
The pectoral girdle consists of a series of membrane bones, connected with 
the skull at the upper part, forming the anterior border of the abdominal 
cavity, and at the same time supporting the pectoral fin, it receives the 
hypaxial portion of the lateral muscle from the cephalic region and some 
succeeding anterior myotomes. 
The post-temporal is a small forked bone. The dorsal branch is flattened 
and rests on the epiotic, while the ventral branch is articulated to a median 
knob of the opisthotic. The ventral branch is round or oblong in cross- 
section and hollow at the anterior end. The branch is produced to a short 
process posteriorly. In the Scombridae we find a long free bifid process 
between the dorsal and ventral branches and exterior to the dorsal branch. 
In Acanthocybium a similar forked auxiliary process is found, partly 
attached to the exterior side of the dorsal branch. In the other forms of the 
Cybiidæ, the auxiliary process is not found, and the cross-section of the 
ventral branch is oblong. The dorsal and ventral processes are connected 
at their root with a thin lamella. The posterior lamellar portion of the bone is 
produced forward very little. The interior ridge, continuous to the ventral 
branch ends with a free point in the genus Sarda. 
In the Plecostei the post-temporal is well developed, and the interior ridge 
continuous to the ventral process ends with a free process. In the Thunnidæ 
the ventral branch is thick and rounded in cross-section. The lamellar portion 
