THE CATFISHES OF VENiEZUELA — ^SCHULTZ 257 



2b. No nasal or mental barbels; mouth inferior; anal short, of 7 to 11 rays, its 

 origin usually behind, rarely under that of dorsal; lower barbel at angle 

 of mouth minute; eyes superior. 

 3a. Mouth wide, teeth very numerous, in several very regular series; rami 

 of lower jaw transverse, meeting, with teeth along its entire length; 

 premaxillary large. 

 4a. Accessory caudal rays few, not conspicuous; caudal not fan-shaped or 

 excessively contracted at base; upper tip with fine, hairlike, movable 

 teeth. 

 5a. Gill membrane confluent with isthmus; gill openings reduced to a 

 narrow slit in front of pectoral; opercle with 4 to 12 spines. 

 6a. Caudal emarginate or obliquely rounded, origin of pelvics nearly 

 equidistant from base of caudal iin and snout to opercle; color, 



if present, in spots Komoiiaetus Eigenmann and Ward 



66. Caudal rounded; few accessory rays; origin of pelvics l}i to 2 

 times as far from snout as from caudal. 



7a. Eyes superior and close together Steg'ophilus Reinhardt 



75. Eyes large, far apart, and lateral Haemomaster Myers 



5b. Gill membrane, united free from isthmus Acanthopoma Liitken 



4b. Accessory caudal rays very numerous, tail like that of a tadpole, base 

 of caudal very narrow; no hairlike teeth on upper lip. 



Ocliinacanthus Eigenmann 



3b. Mouth narrow, rami of lower jaw not transverse, teeth few, feeble, not 



meeting in middle; a few depressible teeth in a single series in middle 



of upper jaw; mandibles without teeth, or with a few excessively 



minute teeth on ends of rami; caudal rounded to emarginate; long, 



slender fishes Vandellia Cuvier and Valenciennes 



16. Anal long with 15 to 25 rays; its origin in front of that of dorsal fin; eyes 

 lateral, seen as well from above as from below. (Tridentinae.) 



Tridensimilis, new genus 



Subfamily Stegophilinae 



Genus PYGIDIUM Meyen 



Trichomycterus Valenciennes, in Humboldt, Recueil d 'observations de zoo- 

 logie . . . , vol. 2, p. 348, 1811 (non Thrichomyc'erus Humbo'dt). 



Pygidium Meyen, Reise um die Erde, vol. 1, p. 475, 1834 (ref. copied from 

 Neave). (Type, Pygidium fuscum Meyen.) 



KEY TO THE SPECIES OF PYGIDIUM REPORTED FROM VENEZUELA 



la. Caudal fin rounded; maxillary barbels slender, reaching to middle of pectoral 

 rays; nasal barbel short, reaching a little past eye or about halfway to 

 end of operculum; origin of dorsal a trifle closer to base of midcaudal fin 

 rays than to tips of branched rays of pectoral; insertion of pelvics equal 

 distance between base of midcaudal fin rays and end of operculum; length 

 of upper prolonged pectoral ray IJ-^ times m distance from its tip to inser- 

 tion of pelvics; a vertical line through origin of dorsal passes a little closer 

 to insertion of pelvics than to anus; color pattern of dark diffuse spots or 

 blotches, no lateral band Pygidium meridae (Regan) 



16. Caudal fin emarginate or a little concave; teeth all pointed, no incisors, on 

 jaws. 

 2a. Color plain or sides with one or more continuous dark bands, but no dark 

 spots on back or sides. 



