COMPARATIVE STL'DY OF SCOJLBKOID ILSHES. 



321 



The paliitine lies on the extoriLil side of the vomer and holds the hoinl 

 of the masilhiry fiist, with the bent :iud nearly hifurcjited anterior end. In 

 the Scombridne the bone is nejirly fiat in the plane of the mesopterj-goid ; 1 >ut 

 in the other scombroid fishes its free ventral margin is generally armed witli 

 teeth on a ridge, projecting and more or less vertical to the principal part /of 

 the pah^tiue, and also to the plane of the mesopterygoid. 



The pterygoid is generally a T-aluiped bone, united to the palatine with 

 a slender horizontal shaft. The posterior end is expanded and joins to the 

 inner side of the metapterygoid and quadrate, with a rough surface. 



The mesopterygoid is a flat thin bono united to the palatine and 

 ptt^rygoid, and rests on the parasphenoid with the? internal free margin, v It is 

 veiy remarkable that the bone is armed with an elliptical patch of: villous 

 teeth at its centre in the Tliunnidie, as the bone is not armed with teeth in 

 other fishes. 



The hyomandibular is a stout bono, with a broad up^x^r portion, and a 

 more or less rod-Uke lower portion. The broader jwrtion has three conspicuoiLs 

 condyles, of which the anterior and middle are for the cranium, and the 

 IKsterior one for the opercle. In the Scombridas the hyomandibular is broad, 



Fig. B. External view of the hyomandibulnr. 1, Scomber jnpimicus; 2, AcatMocyliiwn sotan- 

 dri; 3, Cyb'mvi niiihwnum; 4, Sarda orientalis; 5, Xeothunmis macropterus; 6, Eatsuironns pelamis. 



