with the lateral ethmoid; nuchal shield present; epiotics prominent, with posterior 

 processes and sutured to both nuchal plates; posttemporal absent; supracleithrum 

 with the upper limb sutured to the pterotic and epiotic, and with the lower limb 

 sutured to the basioccipital and exoccipital. In addition, he discussed features of the 

 anterior axial skeleton that are intimately associated with the dorsal fin and rear of 

 the the skull. Although Regan's (1911) characterization of the doradoid skull 

 included important details useful in distinguishing the included taxa from other 

 families, his analysis was much too superficial to adequately diagnose the ageneiosid 

 cranium. Structures of doradoid neurocrania were described, subsequently, in 

 studies of doradids (Eigenmann 1925) and auchenipterids and ageneiosids (Britski 

 1972, Ferraris 1988). In addition, a number of other sources included cursory 

 observations on aspects of a limited number of doradoid taxa. 



Both Britski (1972) and Ferraris (1988) presented detailed morphological 

 descriptions of the ageneiosid skull, but both authors examined relatively few 

 species, and, in some cases, their identifications of the species are questionable due 

 to the previously confused taxonomy of the family. In both studies, the ageneiosid 

 neurocranium was compared with that of several auchenipterid taxa, and 

 generalized characterizations were made at the genus level. The above two studies 

 have provided the greatest amount of information about the ageneiosid 

 neurocranium to date. The only other studies that presented any significant 

 information about the ageneiosid skull were those of Chardon (1968), Howes 

 (1983), and Royero (1987); in each of these cases, limited comparisons were made 

 between ageneiosids and other catfishes. The only previous illustrations of 

 ageneiosid neurocrania were those of A. ucayalensis (Chardon 1968), v4. atronasus 

 (Britski 1972),^. vittatus (Royero 1987), amdA. brevifilis (Ferraris 1988). 

 :, . : The neurocranium of ageneiosids is elongate and considerably depressed, 

 with a relatively broad 'T' formed anteriorly by tiie mesethmoid, and an hourglass- 



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:.,:* 



