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TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



of the mandible, the crowding back of the mesopterygoid (which is thrust in between the 

 quadrate and the hyomandibular), the verticality of the pterygo-quadrate border. The 

 roof of the mouth is raised; hence the hyomandibular is much reduced vertically and the 

 opercular and subopercular are remarkably small, while the symplectic and preopercular 

 are prolonged with the downward and forward growth of the quadrate-articular pivot. 

 The cerato-, basi-, and uro-hyals are enlarged vertically, while the glossohyal is very small; 



pf SpareVh 



Zeus japonicus 



Fig. 148. Zeus japonicus. 



the lower pharyngeals are rather small and separate; they bear oval vestigial patches 

 (Starks, 1898^, PI. XXXIV). 



Some of the features that are associated with protrusility of the premaxillae are shared 

 by Zeus with the chaetodontoids but the relationships are evidently not very close. 



Capros. — The boar-fish Capros aper (Fig. 149^) has a strongly compressed body with 

 a small, extremely protrusile mouth, the ascending processes of the premaxillae being several 

 times longer than the small dentigerous portion. The maxillary is a bone of unusual com- 

 plexity, with a broad twisted blade and a great forwardly directed dorsal hook which 

 embraces the ascending process of the premaxilla. The dentary is very short and has a 

 secondary joint with the elongate angular-articular, after the fashion of fishes with small 

 nibbling mouths. The downward movement of the articular, by the action of the longi- 



