The paired lateral ethmoids are large and highly porous (Figs. 3-7). 

 Anteroventrally they form large cartilaginous blocks encircling the nasal capsule. 

 Dorsally the lateral ethmoids are broadly expanded and suture medially with the 

 mesethmoid and frontals. The antorbital process is generally ossified except for a 

 cartilaginous facet for the palatine. The mesopterygoid articulates with a shallow 

 groove on the posteroventral margin of the lateral ethmoid. A dorsomedial ridge of 

 the lateral ethmoid contacts the frontal anteriorly and forms a small portion of the 

 bony orbit. ,-, , .* • . . . :. 



The frontals suture deeply to the mesethmoid and lateral ethmoids anteriorly 

 (Figs. 3-6). The frontals are strongly constricted at their middle and expanded 

 posteriorly. There is a large cranial fontanelle, corresponding to the anterior 

 fontanelle of many other catfishes, beginning at the posterior end of the 

 mesethmoid and extending to about the narrowest constricted area of the frontals. 

 The frontals are sutured at their midline posteromedially, and the fontanelle is 

 continued as a shallow groove above the suture. There is no posterior fontanelle. 

 Posterolaterally the frontals contact the sphenotics, and posteromedially they suture 

 deeply to the supraoccipital. Ventrally the frontals contact the orbitosphenoids, 

 parasphenoids, and pterosphenoids. 



. ^ ^ The supraoccipital is large and broadly rounded, and usually ornamented 

 with weak ridges or rugosities. Anterolateral^ the supraoccipital meets the 

 sphenotics. Most of the lateral margins of the supraoccipital suture with the paired 

 pterotics, which are relatively large and roughly quadrangular in dorsal profile. The 

 epioccipitals extend dorsally and contact the supraoccipital to form the 

 posterolateral margin of the neurocranium. The posterior margin of the 

 supraoccipital sutures with the broad anterior margin of the nuchal shield, formed 

 by the dermal component of the first dorsal-fin pterygiophore (discussed under the 

 dorsal fin morphology). 



