34 PROCEEDINGS OF THE NATIONAL MUSEUM vol.. ra 



the infraorbital canal up to its junction with the supraorbital canal 

 (three of these are slightly larger than the others and may represent 

 the usual percoid circumorbital bones). 



The supraorbital canal starts in a tubular nasal bone that is attached 

 movably to the frontal behind it. The canal then passes back through 

 the frontals, giving off two major lateral exits and one median. The 

 median exit apparently represents the interorbital commissure; on 

 each side, it passes in through a low frontal rise and opens out onto 

 the surface of the skull on the interior slope of this rise; the open- 

 ing is covered with a membrane, and there is no sign of any connection 

 between canals of the two sides of the head. 



The temporal canal extends the full length of the pterotic in a 

 trough, open externally. The preopercular canal joins the temporal 

 canal via a membranous tube. 



Jaws. — The upper jaw is distinctly protrusile. The usual ethmoid- 

 maxillary and palatine-premaxillary ligaments are present. 



The maxillary has a long, subtriangular supramaxillary. 



The premaxillary is uot beaklike. Its ascending process is nearly 

 vertical, with the usual deep groove between it and its well-developed 

 if low articular process over which the maxillary head rides. 



Suspensorium. — The top of the interopercle and the lower portions 

 of the subopercle and preopercle have weak serrations. There are two 

 weak points on the opercle separated by a deep indentation; above 

 the upper of these, the opercular edge is more or less ragged edged. 



There is no metapterygoid lamina (cf. Katayama, 1959). 



Hyoid apparatus. — There are seven branchiostegals on each side, 

 not six as reported by Roule (1922). 



There is a groove along the epihyal continued forward into the 

 ceratohyal, also one anteriorly on the ceratohyal; the grooves at the 

 two ends of the ceratohyal are connected by a completely enclosed 

 tunnel. 



The usual gill arch bones are present. 



There is a well-developed pseudobranch. 



Cranium. — The inner face of the maxillary head rides on the side of 

 the vomerine portion of the ethmovomerine keel. The ethmoid con- 

 tributes to the keel but also has a broad, flat upper portion under and 

 between the frontals. 



Posteriorly, the frontals become slightly raised medially. Appressed 

 against a portion of the lower surface of this rise is the "pineal organ" 

 (Rivas, 1953). Laterally, there are two low ridges over the supra- 

 orbital canal. The whole top of the skull looks like that shown by 

 Matsubara and Iwai (1958, fig. 5) for Ruvettus. 



The parasphenoid is slightly arched. There is no posterior opening to 

 the myodome. 



