322 K.UIAKICHI KISHINOUYE : 



;iucl tluj anterior margin of the upj^ier broad poi-tion convex and entire. Tlie 

 condylar protuberances are rather small, not prominent, the anterior one 

 scarcely produced beyond the broad lamellar part, but the posterior one 

 remarkably outstretching liehind. Moreover these protuberances are nearly in 

 one plane. The stem of the hyomaulibular is grasped by the bifurcated end 

 <jf the metapterygoid. lu the CA^biidiTB the upper portion of the hyomandibular 

 becomes narrow, and the anterior ct)udylo is couspicuously produced beyond 

 the lamellar portion. The lower portion is rod-Hke, and the exterior longi- 

 tudinal ridge for the attachment of the preopercle is rather jirominent, and is 

 ]iroduced 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 Ijehind the middle condyle iu 

 the scombroid fishes, except iu mackerels. Tlie anterior vertical margin of the 

 upper portion is free ; but its lower margin is horizontal and dentate for tho 

 articulation with tho metapterygoid. Iu the Plecostei the lamellar portion 

 has become very narrow, but the lower articulating margin for the metapterygo'd 

 is broad, sa that the lower margin gi-eatly projects. Tlie lower poi-tion is bent 

 a little forward, and is flat and broad, especially iu the genus Attxis. The 

 exterior posterior longitudinal ridge for the attachment of the preopercle is 

 oblique, and does not reach the dorsal mai'giu of the broad part. The small 

 secondary ridge is developed behind the first, anl below the posterior condyle. 

 Tho last condyle is best developed- and is turned exteriorly. The process 

 t;an-ying the anterior condyle is more or less rouudish in cross-saction in 

 Tlmnnus ; but more or less flattened iu ParcdJtunnus and Xeothunnus, and in 

 the KatsuwouidiB the process is tm'ued at the dorsal and ventral margins. The 

 lower half of the hyomandibular is broad, flattened, and very thin in the 

 Katsuwoiiid». 



The metapterygoid is a bn)ad bjU(\ with the dorsal cud bifurcated to 

 gi'asp the stem of the hyomandibular, and bordei-s the quadi'ate with a broad, 

 smooth margin, being connected with a narrow intervening cartilage. The 

 shape of the bone differs only a little in diflerent kinds of the scombroid 

 flshes. Li RaslrcUifjcr this bone is attached to the ptarygoid. In Scomber 

 the inner branch of the bone extends even over the preopercle. Generally 

 spaakiug tlio bifurcation of the bone is not conspicuous in the C'ybiida?. Tlie 



