forms part of the posterior portion of the neurocranium. Dorsally the epioccipital 

 forms a small plate that is sutured posterolaterally with the posttemporal, 

 anterolaterally with the sphenotic, and medially with the supraoccipital (Figs. 3-6). 

 In most auchenipterids and all ageneiosids, the epioccipital has prominent 

 posteriorly directed spines or processes. In several taxa, the posterior extensions of 

 the epioccipital contact the complex centrum of the Weberian apparatus. In 

 auchenipterids, the length of the epioccipital spine(s) and degree of fusion with the 

 vertebral centra varies among genera and has been used to unite some taxa 

 (Ferraris 1988, Curran 1989). In ageneiosids, the epioccipital process is 

 considerably more extensive than in most auchenipterids, and may represent the 

 most derived configuration. In ageneiosids, the posterior process of the epioccipital 

 is fused medially with broadly expanded parapophyses of the fifth and six vertebra; 

 the entire structure forms a broad, laminar shelf extending from the posterior 

 margin of the neurocranium to the center of the complex centrum (Figs. 3-8, 24). 

 Near the posterior medial end of the epioccipital, where it contacts the 

 parapophyses of the fifth and sixth vertebrae, there is a large foramen; a medial 

 ramus of the vagus nerve (vagus lateralis of Howes 1983) passes across the 

 MuUerian ramus dorsolateral^, then passes through the foramen and extends 



■ " « ■ 



laterally along the vertebral column (Fig. 17). 



^ I add the following anecdotal comments on sensory reception in ageneiosids. 



Assuming that olfactory acuity may be diminished as a consequence of the reduced 

 barbels, one is left to speculate that perhaps ageneiosids have compensated for 

 sensory reception in other ways. Little is known of their ecology, and virtually 

 nothing is known about their physiology. At least some species are active both 

 diumally and noctumally. The eyes and optic centers of the brain are moderately 

 well developed, thus vision is probably fairly acute. The lateral line is also well 

 developed, and the acousticolateraUs canals on the head are moderately developed, 



