COMPARATIVE STUDY OF SCOMBROID FISHES. 
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Katsuwonidæ the exterior wing is nearly vertical to the interior wing, and 
there is a groove along the external margin of the exterior wing. 
Between the pointed process and the posterior lameller part of the dorsal 
end of the clavicle there is a narrow slit, through which the transverse 
clavicular ligament, binding the axial skeleton with the supraclavicle passes. 
The posterior margin of the pointed process is rounded and smooth. To the 
clavicular ligament, a small ligament joins running along the anterior margin 
of the broad dorsal end of the clavicle. 
The hypercoracoid is a small flat bone articulated to the clavicle at the 
upper, interior side, and has a round foramen near the centre of the bone. 
The hypocoracoid is united to the hypercoracoid above and also to the clavicle 
at the dorsal anterior comer. In the Scombridæ this bone has an external 
longitudinal keel, and the lower styliform process is long and narrow. In the 
Cybiidae the bone is broad and has a 
median longitudinal groove, or rather 
the bone is bent externally along the 
longitudinal axis. The low r er process is 
rather broad. In Cybium and Sarda 
the central foramen is very small, but 
it is large in Acanthocybium and Gyrn- 
nosarda. In the Plecostei the lower 
process is broad, uniformly thin, 
and folded more deeply than in 
the Cybiidae. Four actinosts basalia 
or brachial ossicles are found upon 
the hypercoracoid and hypocoracoid 
to support the pectoral fin. They 
become larger as they approach 
posteriorly. In the Scombridae there 
is no foramen between the last ossicle 
and the dorsal posterior process of 
the hypercoracoid ; but in all the other scombroid fishes we find a foramen 
there. 
The postclavicle is composed of two pieces of bones, and protects the 
Fig. H. External view of the left lower 
piece of the postclavicle. 
1, Scomber japonicus ; 2, Ggbium niphonium 
3, Thunnus orientalis ; 4, Katsuwonus pelamis. 
