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KAMAKICHI KISHINOUYE : 
and the anterior margin of the upper broad portion convex and entire. Tire 
condylar protuberances are rather small, not prominent, the anterior one 
scarcely produced beyond the broad lamellar part, but the posterior one 
remarkably outstretching behind. Moreover these protuberances are nearly in 
one plane. The stem of the liyoman libular is grasped by the bifurcated end 
of the metapterygoid. In the Cybiidæ the upper portion of the hyomandibular 
becomes narrow, and the anterior condyle is conspicuously produced beyond 
the lamellar portion. The lower portion is rod-like, and the exterior longi¬ 
tudinal ridge for the attachment of the preopercle is rather prominent, and is 
produced sometimes beyond the dorsal margin of the broad portion. The posterior 
condyle approaches the middle condyle, and the former is more or less turned 
exteriorly. A small pointed process is found behind the middle condyle in 
the scombroid fishes, except in mackerels. The anterior vertical margin of the 
upper portion is free ; but its lower margin is horizontal and dentate for the 
articulation with the metapterygoid. In the Plecostei the lamellar portion 
has become very narrow, but the lower articulating margin for the metapterygoid 
is broad, so that the lower margin greatly projects. The lower portion is bent 
a little forward, and is flat and broad, especially in the genus Auxis. The 
exterior posterior longitudinal ridge for the attachment of the preopercle is 
oblique, and does not reach the dorsal margin of the broad part. The small 
secondary ridge is developed behind the first, and below the posterior condyle. 
The last condyle is best developed and is turned exteriorly. The process 
carrying the anterior condyle is more or less rouudish in cross-section in 
Thunnus ; but more or less flattened in Paratliunnus and Neothunnus, and in . 
the Katsuwonidæ the process is turned at the dorsal and ventral margins. The 
lower half of the hyomandibular is broad, flattened, aud very thin in the 
Katsuwonidæ. 
The metapterygoid is a broad bone, with the dorsal end bifurcated to 
grasp the stem of the hyomandibular, and borders the quadrate with a broad, 
smooth margin, being connected with a narrow intervening cartilage. The 
shape of the bone differs only a little in different kinds of the scombroid 
fishes. In Bastrelliger this bone is attached to the pterygoid. In Scomber 
the inner branch of the bone extends even over the preopercle. Generally 
speaking the bifurcation of the bone is not conspicuous in the Oybiidæ. The 
