95] THE SKULL OF AM I URUS— KINDRED 95 



larger than the subtemporal. Sagemehl (1885) states that these bones are 

 present in many of the Siluroids. 



The opercular apparatus. This consists of three bones; a large dorsal 

 operculum and two smaller ventral bones, the inter- and suboperculum, (Fig. 

 15). The operculum spreads out posteriorly in a wide arch and articulates 

 anteriorly with the hyomandibular knob. It is heavily sculptured on its 

 external surface, tapers ventrally, and at its inferior apex the short quadrangular 

 interoperculum is attached by ligamentous tissue and interpolated between it 

 and the posterior end of the articulare. The suboperculum is smaller and lies 

 medial to the interoperculum. 



